While I was picking up my IBC Totes yesterday I had a chance to speak with the operations manager at this olive oil importer and distributor. There were 10s of thousands of IBC totes at this location. Many of them were empty, some were full of balsamic vinegar and some were full of olive oil. I had mistakenly thought that the olive oil was transported to this location in the IBC totes. In fact, only the balsamic vinegar which they also distribute comes in the Totes. The oil, as it turns out, comes shipped in cargo containers that are 20 ft. by 8 ft. and about 8 ft. high. The container is filled with a heavy duty plastic bladder that will hold 6,000 gallons. When the container arrives they off-load the olive oil into the IBC totes. Then they remove the bladder from the cargo container and hang it so that the oil drains out. They have found no way to dispose of these bladders other than the landfill. They are obviously capable of holding water. They cost about $1,000 new and are not reused. They are thrown out. In the case of the IBC Totes the plastic and the metal can all be recycled, but not so with the bladders because it is so difficult to get all the oil out efficiently. I was thinking that the bladder could potentially be installed and then cleaned in situ with some sort of detergent or degreaser.
The bladders cannot be just placed on the ground and filled with water. I think they must be contained in something -- either a steel cargo container with supplemental bracing from side to side or possibly with just a hole in the ground.
The distributor is going to give me one to experiment with. I think I can get one when it is folded up into a pickup truck. I don't really want to dig a hole in my yard that is 20 x 8 and 8 feet deep, even if the bladder is free. And I certainly don't want to put a steel shipping container in the yard (I understand these can be had for under $1,000.) While this would be a bit cheaper than the IBC totes that I have been using, they would be far less flexible and yard friendly.
If anyone has any bright ideas about these bladders please chime in and let's talk about the possibilities.
MY WATER CONSERVATION SYSTEMS. I started with the design and implementation of a Rainwater Catchment System for my home. It was then expanded to cover a gray water system, and then started getting into a fog harvesting system. I suggest that you start with the oldest entry first and work your way forward in time. I frequently go back and modify my blog entries to reflect current thinking and to remove errors. If I have modified an entry I have a "last modified" date at the end of the entry.
Tuesday, December 9, 2014
Installing the Secondary IBC Tote Storage Tanks
The storm this last week dumped just over 9 inches of rain here. Unfortunately, my primary storage tanks are already full and I could not capture any new water. This situation will not be lasting much longer.
I have now purchased 20 additional IBC totes (265 gallons ea. x 20 = 5,300 gallons) and the necessary PVC piping to hook it into the remaining downspouts, the irrigation system, and electric cable for the pump. This will bring my total capacity to 6,400 gallons. The tanks I got this time cost $40 each and the truck rental to get them here added another $5 to the cost of each. (Total cost for these 20 tanks is $900 including transportation.)
The images immediately below are various views of the in process installation. The most labor intensive part was leveling out three levels of terraces area to hold the tanks and building retaining walls. As you can see, the lowest level tanks are now in place, there is one tank each at the second and third levels. I have also used one tank as a short term holding tank for rainwater as it comes off the roof before it is pumped into the tanks. I had to do this in order to get the water into those tanks since the gravity feed brought the water in too low to fill just by gravity. I will use the same holding tank to pump the water into the irrigation system when necessary.
I have not purchased the enclosure material to cover the tanks nor the pump yet, but will do so very shortly. I have already trenched out the ditch for the various pipes and electric line to bring the downspout water to the new tank location. I will set the IBC totes in place and lay the drain line within the week. Unfortunately, the water from the major storm coming this week will not get into my tanks. This one storm would most likely fill them to the brim. C'est la vie. It will have to be the next storm that fills them. I suspect that when all is done I will have spent another $800 for these other materials. So, total cost will be about $1,700 for the 5,300 gallons. That's around 32 cents per gallon installed.
For the primary storage tanks I have found it useful to have a valve to redirect the water from the original drain to the IBC totes. This is useful when the tanks are completely full. The overflow for those tanks can't really handle multiple storms. It just wasn't built for that. Given the success I have had with this method, I think I will do the same with the secondary storage. (By way of explanation the primary and secondary storage systems are on opposite sides of the house and pick up the water from different downspouts, so I do need two such valves, unfortunately, since they are somewhat expensive).
I found it difficult to find out where the existing underground drainpipe is under the yard.
I have found it useful to have an electrical snake to insert in the drain at the point where the downspout goes into the ground in order to determine how far it is to the first elbow or tee in the drain. That way, once I know the direction the drain is going I can determine where the pipe is underground at the change in direction. This doesn't answer every question, but was useful in cutting down on the number of test holes I had to dig.
Since I am going to be stacking the totes (2 high) and the location is not that far below ground level I am going to have to pump the water up into the tanks when it rains. I will use a sump pump with an automatic on/off switch that is activated by the water level. I am going to use this same pump to pump water into the irrigation system in order to get the pressure that I need to run through that system. I will have to have a few valves to open and shut in order to accomplish this. Haven't worked it all out completely yet, I will post a sketch of how it finally ends up in case you are interested.
I have not been too happy with my filtration system on the primary storage tanks. I have had to clean it out from getting clogged up three times already. The very fine grit is coming off my roof and really does a number on the filters. I have probably removed 20 lbs. of this stuff already since the rainy season started in September. I think I will just have to clean it out after each rain (2-3 inches of rain). It only takes a few minutes so it isn't the end of the world, given how much water I am harvesting.
One further note, when I put in the trench to divert the rain water to the secondary set of totes, I inadvertently went slightly uphill in one section. This was just enough to prevent the water from flowing by gravity to the new tanks. Consequently, I have dug the trench a little deeper in that section to avoid this problem. I should have known that water will not run uphill, unless it is a siphon or under pressure.
I have now purchased 20 additional IBC totes (265 gallons ea. x 20 = 5,300 gallons) and the necessary PVC piping to hook it into the remaining downspouts, the irrigation system, and electric cable for the pump. This will bring my total capacity to 6,400 gallons. The tanks I got this time cost $40 each and the truck rental to get them here added another $5 to the cost of each. (Total cost for these 20 tanks is $900 including transportation.)
The images immediately below are various views of the in process installation. The most labor intensive part was leveling out three levels of terraces area to hold the tanks and building retaining walls. As you can see, the lowest level tanks are now in place, there is one tank each at the second and third levels. I have also used one tank as a short term holding tank for rainwater as it comes off the roof before it is pumped into the tanks. I had to do this in order to get the water into those tanks since the gravity feed brought the water in too low to fill just by gravity. I will use the same holding tank to pump the water into the irrigation system when necessary.
 |
| This is the holding tank (not hooked up yet) |
I have not purchased the enclosure material to cover the tanks nor the pump yet, but will do so very shortly. I have already trenched out the ditch for the various pipes and electric line to bring the downspout water to the new tank location. I will set the IBC totes in place and lay the drain line within the week. Unfortunately, the water from the major storm coming this week will not get into my tanks. This one storm would most likely fill them to the brim. C'est la vie. It will have to be the next storm that fills them. I suspect that when all is done I will have spent another $800 for these other materials. So, total cost will be about $1,700 for the 5,300 gallons. That's around 32 cents per gallon installed.
For the primary storage tanks I have found it useful to have a valve to redirect the water from the original drain to the IBC totes. This is useful when the tanks are completely full. The overflow for those tanks can't really handle multiple storms. It just wasn't built for that. Given the success I have had with this method, I think I will do the same with the secondary storage. (By way of explanation the primary and secondary storage systems are on opposite sides of the house and pick up the water from different downspouts, so I do need two such valves, unfortunately, since they are somewhat expensive).
I found it difficult to find out where the existing underground drainpipe is under the yard.
I have found it useful to have an electrical snake to insert in the drain at the point where the downspout goes into the ground in order to determine how far it is to the first elbow or tee in the drain. That way, once I know the direction the drain is going I can determine where the pipe is underground at the change in direction. This doesn't answer every question, but was useful in cutting down on the number of test holes I had to dig.
Since I am going to be stacking the totes (2 high) and the location is not that far below ground level I am going to have to pump the water up into the tanks when it rains. I will use a sump pump with an automatic on/off switch that is activated by the water level. I am going to use this same pump to pump water into the irrigation system in order to get the pressure that I need to run through that system. I will have to have a few valves to open and shut in order to accomplish this. Haven't worked it all out completely yet, I will post a sketch of how it finally ends up in case you are interested.
I have not been too happy with my filtration system on the primary storage tanks. I have had to clean it out from getting clogged up three times already. The very fine grit is coming off my roof and really does a number on the filters. I have probably removed 20 lbs. of this stuff already since the rainy season started in September. I think I will just have to clean it out after each rain (2-3 inches of rain). It only takes a few minutes so it isn't the end of the world, given how much water I am harvesting.
One further note, when I put in the trench to divert the rain water to the secondary set of totes, I inadvertently went slightly uphill in one section. This was just enough to prevent the water from flowing by gravity to the new tanks. Consequently, I have dug the trench a little deeper in that section to avoid this problem. I should have known that water will not run uphill, unless it is a siphon or under pressure.
Friday, October 10, 2014
Protecting the IBC Totes from Light
I am actively working on the secondary water storage system. I am going to be adding 20 tanks in two rows of 10 tanks, with 10 on top of the 10 on the ground level. I have already cleared and leveled the area that I want to place the tanks. It is located next to a fence (6 feet high). The tanks will be almost 8 feet in height, so I am going to raise the fence another two feet to act as the light barrier on that side. I will still have to protect the tanks from light on all the other sides.
On the primary tanks I used hardy board and steel stakes hammered into the ground to construct the shell. I think that for this bank of tanks I will try to use a more simple and cost effective material.
Let us review the situation. We have to protect the tanks from UV light infusion or else we will have algae buildup in the tanks and deterioration of the polyethylene tanks themselves. Next, the material that we use for this purpose must be able to withstand the damage that UV light can produce.
One of my neighbors, who is also installing rainwater IBC totes, found these covers:
On the primary tanks I used hardy board and steel stakes hammered into the ground to construct the shell. I think that for this bank of tanks I will try to use a more simple and cost effective material.
Let us review the situation. We have to protect the tanks from UV light infusion or else we will have algae buildup in the tanks and deterioration of the polyethylene tanks themselves. Next, the material that we use for this purpose must be able to withstand the damage that UV light can produce.
One of my neighbors, who is also installing rainwater IBC totes, found these covers:
The website for buying them is here. They sell for about $60 each, depending upon exactly how many you buy. I personally think that is expensive and I am concerned about their durability. The website says that they are made of a PVC material. My understanding is that while the PVC may be good for protecting the inside from UV light, the material itself is not durable for UV applications (i.e., the material will deteriorate if exposed to UV light and will have a short lifespan). I have not verified this last suspicion. That having been said, I thought I would include it here for those of you who have any sewing skills. I am researching materials that could be used and will post anything I find that is interesting. Note, if sewing fabric to assemble a Tote caddy, please use the special UV thread that is available (used for outdoor cushions) or you may have durable material coming apart at the seams as the UV deteriorates the thread more rapidly than the fabric.
I have found a high impact polystyrene (black) that would make a wonderful outer shell, but I still have to figure out how to seam it since you could not use a sewing machine for this.
I did find this YouTube video that describes using black plastic sheeting. I again stress that the material used must be able to withstand deterioration from UV light. I don't think the material used in this video is that type of material.
Wednesday, August 13, 2014
Gray Water Irrigation System
The construction of the gray water irrigation system here at the house is functioning on an experimental basis and is almost completed. We have departed from the standard or recommended design for the distribution of the water into the garden with this system. We did this primarily because we do not want to create the larger pits filled with mulch or gravel for the water that percolate into the ground as is usually done. We want to use flexible irrigation hoses with holes in the line near each one of the plants with small gravel or mulch basins near each hole in the flexible water hose. We think this will be more efficient, but the holes may get clogged. We still consider this approach very experimental. I will report on the success of this method once we have it working with a little time under our belt operating it.
The gray water that we are capturing is the water from the laundry and one bathtub/shower and the bathroom sink. We may add one other shower to this system, but that one is used very infrequently and it may not be worth running a pipe that far (Note: I may add that shower as an alternative to my taking a shower in the bathtub). Also, we do not think that we can effectively use that additional water as it might exceed the capacity of the system. Also, we are not adding the gray water from the master bathroom because it is on the second floor and we would have to open up too many walls to separate the gray water from the black water.
We have decided to bathe downstairs so that we can capture this gray water. This will be primarily during the summer months when we have the largest need for water in the garden and very little rainwater.
(Note: this comment was added after the system had been installed and was running for a while. Now that the system is operational, I am running the drain line from the shower to the gray water systems. This will not increase the load on the system as I will be not taking a shower in the bathtub and, instead, showering in the shower stall. Total cost for the additional run turned out to be about $15. 00 for the convenience of taking the shower there.)
Capacity
We do about six loads of washing a week, at 15 gallons per load. We have a front loading high efficiency washing machine. Figure about 90 gallons a week for this. For this system, however, it will be far more meaningful to talk about daily usage, since we do not want to flood the garden with too much gray water at one time. We normally do no more than two loads in the washing machine a day (2 loads = 30 gallons).
There are two of us in the house and we either take a shower or a bath. Figure about 20 gallons for a shower (my showers are usually only 5 minutes long and should only use about 10 gallons) and about 30 gallons for a bath. I generally take the quick shower, my wife tends to take the bath. So, figuring that on a typical day we each bathe, that is another 50 gallons of water or less. I have to assume for computing the capacity that this is on the same day as the 30 gallons or water for the washing machine.
In summary, for a typical day when the laundry is done we might use:
Washing machine 2 loads 30 gallons
Bath 1 30 gallons
Shower 1 20 gallons
Total 80 gallons
Now, we know that this is not going to be all used at one time, so we are going to build the system to handle a maximum of about 40 gallons in one hour.
Gray Water Storage Capacity
It is not a good idea to store gray water for more than a day. We want to merely store that larger quantity of water for, say, at most an hour or so to let it permeate the ground, instead of running off on the surface if it is discharged too rapidly. We are building the system to handle about 40 gallons an hour, but do not expect to be using 40 gallons in one hour very frequently (at most 3 times a week), and most other times there will be no or very little water going through the system.
The Garden
We have chosen a large succulent and cactus garden that we have constructed that we currently hand water. The Garden is about 320 sq. ft. in size. It is located downhill from the house and about 60 feet away from the house.
The Storage Tank
We have departed from the typical storage tank concept and decided to use the drainage pipe itself as the storage device. There are approximately 55 feet of 4 inch diameter drainage pipe once the water leaves the house. There is also about 20 feet of 2 inch pipe running along the foundation leading down to the 4 inch pipe. The storage capacity in the pipe is as follows:
55 ft. of 4 inch pipe = 4.80 cu. ft.
20 ft. of 2 inch pipe = .44 cu. ft.
Total capacity 5.24 cu. ft. = 39.20 gallons
Water Distribution to the Plants
At the base of the pipe just as it approaches the garden from the house we have installed a large irrigation box. You can see the green cover plate for that box in the picture above. Immediately before entering the irrigation box the pipe changes back from a 4 inch pipe to a 2 inch pipe. In the box we have an inspection window in the pipe made from clear plastic tubing the same diameter as the pipe. Then, following the window there is a manifold. The header is made of 2 inch plastic pipe. We have drilled 5 holes, each 3/4 inches in diameter into the manifold and inserted nipples and connected the black flexible 1/2 inch irrigation tubing to the nipples. The flexible tubing weaves between the plants underground (Note: since I am still experimenting the tubing is above ground as you can see in the picture above). Also note that there are a number of bends in the pipe within the irrigation box so that I could fit it all in there. Obviously, if you have a different setup you may be able to do this without all the elbows I had to install.
The flexible tubing has holes near each of the plants to be watered.
The amount of water that will be distributed to the plants on a square foot basis is computed as follows:
If you assume that he water is distributed evenly over the 320 sq. ft. area of the garden, then, on laundry day (80 gallons of water) the amount of water per sq. ft. will be equal approximately 10.5 cu. ft./320sq. ft. = .033 cu. ft../sq. ft. To compute the equivalent rainfall this must be converted to inches. This is 57 cu. in./sq. ft., which translates into the equivalent of .4 in. of rainfall. Since this distribution method will not distribute the water evenly, we are estimating that the equivalent for the areas that are actually receiving the water will be more like the equivalent of 1/2 in. of rainfall. Ideally this level will be achieved at least three times a week, with smaller amounts on days when only the bathing occurs.
Percolation of the Water into the Garden
There are two inspection windows made of clear plastic 2 inch pipe. One window is attached to the manifold down by the garden (see above picture) inside the irrigation box that we just discussed above, and the other is just at the point where the pipe leaves the building (see picture below).
This is exactly the area between which there are about 40 gallons of storage capacity. With the bathtub full of 40 gallons of water I can now test to see how long it takes for the storage pipe to empty (I considered installing a valve in the irrigation box that would allow me to store all the water above the valve, but opted not to do it for fear that I might forget to open the valve when required and thereby cause a backup into my house.)
(Note: Now that the system is in I think it might have been better to put in a bib valve so that I might take water from the garden hose to connect to the system so that I might use the irrigation portion of the system without having to do laundry or take a shower. The only alternative I have without changing the system is to put water into the bathtub and let it flush through the system.)
Gaging from the time it takes to percolate into the ground with a limited number of holes I have now computed that it takes about 10 holes to percolate 40 at gallons per hour. I have installed about 40 holes, so it takes about 15 minutes to distribute 40 gallons of water.
The flexible irrigation pipe is exposed for testing purposes. When testing is completed the hose will be buried and mulch or gravel will be inserted around all the outlet holes near the plants.
Cost
The cost of the project has been about $200 in materials. It took a few days to install.
Other Considerations
I have not yet installed either a bypass valve or an overflow for the system. These matters concern me and I will be addressing them. The main problem with the bypass valve is that I must install one that is electrically controlled as the place where the valve must be located is in the crawl space below the house. More on this later.
last modified 8/17/2014
The gray water that we are capturing is the water from the laundry and one bathtub/shower and the bathroom sink. We may add one other shower to this system, but that one is used very infrequently and it may not be worth running a pipe that far (Note: I may add that shower as an alternative to my taking a shower in the bathtub). Also, we do not think that we can effectively use that additional water as it might exceed the capacity of the system. Also, we are not adding the gray water from the master bathroom because it is on the second floor and we would have to open up too many walls to separate the gray water from the black water.
We have decided to bathe downstairs so that we can capture this gray water. This will be primarily during the summer months when we have the largest need for water in the garden and very little rainwater.
(Note: this comment was added after the system had been installed and was running for a while. Now that the system is operational, I am running the drain line from the shower to the gray water systems. This will not increase the load on the system as I will be not taking a shower in the bathtub and, instead, showering in the shower stall. Total cost for the additional run turned out to be about $15. 00 for the convenience of taking the shower there.)
Capacity
We do about six loads of washing a week, at 15 gallons per load. We have a front loading high efficiency washing machine. Figure about 90 gallons a week for this. For this system, however, it will be far more meaningful to talk about daily usage, since we do not want to flood the garden with too much gray water at one time. We normally do no more than two loads in the washing machine a day (2 loads = 30 gallons).
There are two of us in the house and we either take a shower or a bath. Figure about 20 gallons for a shower (my showers are usually only 5 minutes long and should only use about 10 gallons) and about 30 gallons for a bath. I generally take the quick shower, my wife tends to take the bath. So, figuring that on a typical day we each bathe, that is another 50 gallons of water or less. I have to assume for computing the capacity that this is on the same day as the 30 gallons or water for the washing machine.
In summary, for a typical day when the laundry is done we might use:
Washing machine 2 loads 30 gallons
Bath 1 30 gallons
Shower 1 20 gallons
Total 80 gallons
Now, we know that this is not going to be all used at one time, so we are going to build the system to handle a maximum of about 40 gallons in one hour.
Gray Water Storage Capacity
It is not a good idea to store gray water for more than a day. We want to merely store that larger quantity of water for, say, at most an hour or so to let it permeate the ground, instead of running off on the surface if it is discharged too rapidly. We are building the system to handle about 40 gallons an hour, but do not expect to be using 40 gallons in one hour very frequently (at most 3 times a week), and most other times there will be no or very little water going through the system.
The Garden
We have chosen a large succulent and cactus garden that we have constructed that we currently hand water. The Garden is about 320 sq. ft. in size. It is located downhill from the house and about 60 feet away from the house.
The Storage Tank
We have departed from the typical storage tank concept and decided to use the drainage pipe itself as the storage device. There are approximately 55 feet of 4 inch diameter drainage pipe once the water leaves the house. There is also about 20 feet of 2 inch pipe running along the foundation leading down to the 4 inch pipe. The storage capacity in the pipe is as follows:
55 ft. of 4 inch pipe = 4.80 cu. ft.
20 ft. of 2 inch pipe = .44 cu. ft.
Total capacity 5.24 cu. ft. = 39.20 gallons
Water Distribution to the Plants
At the base of the pipe just as it approaches the garden from the house we have installed a large irrigation box. You can see the green cover plate for that box in the picture above. Immediately before entering the irrigation box the pipe changes back from a 4 inch pipe to a 2 inch pipe. In the box we have an inspection window in the pipe made from clear plastic tubing the same diameter as the pipe. Then, following the window there is a manifold. The header is made of 2 inch plastic pipe. We have drilled 5 holes, each 3/4 inches in diameter into the manifold and inserted nipples and connected the black flexible 1/2 inch irrigation tubing to the nipples. The flexible tubing weaves between the plants underground (Note: since I am still experimenting the tubing is above ground as you can see in the picture above). Also note that there are a number of bends in the pipe within the irrigation box so that I could fit it all in there. Obviously, if you have a different setup you may be able to do this without all the elbows I had to install.
The flexible tubing has holes near each of the plants to be watered.
The amount of water that will be distributed to the plants on a square foot basis is computed as follows:
If you assume that he water is distributed evenly over the 320 sq. ft. area of the garden, then, on laundry day (80 gallons of water) the amount of water per sq. ft. will be equal approximately 10.5 cu. ft./320sq. ft. = .033 cu. ft../sq. ft. To compute the equivalent rainfall this must be converted to inches. This is 57 cu. in./sq. ft., which translates into the equivalent of .4 in. of rainfall. Since this distribution method will not distribute the water evenly, we are estimating that the equivalent for the areas that are actually receiving the water will be more like the equivalent of 1/2 in. of rainfall. Ideally this level will be achieved at least three times a week, with smaller amounts on days when only the bathing occurs.
Percolation of the Water into the Garden
There are two inspection windows made of clear plastic 2 inch pipe. One window is attached to the manifold down by the garden (see above picture) inside the irrigation box that we just discussed above, and the other is just at the point where the pipe leaves the building (see picture below).
This is exactly the area between which there are about 40 gallons of storage capacity. With the bathtub full of 40 gallons of water I can now test to see how long it takes for the storage pipe to empty (I considered installing a valve in the irrigation box that would allow me to store all the water above the valve, but opted not to do it for fear that I might forget to open the valve when required and thereby cause a backup into my house.)
(Note: Now that the system is in I think it might have been better to put in a bib valve so that I might take water from the garden hose to connect to the system so that I might use the irrigation portion of the system without having to do laundry or take a shower. The only alternative I have without changing the system is to put water into the bathtub and let it flush through the system.)
Gaging from the time it takes to percolate into the ground with a limited number of holes I have now computed that it takes about 10 holes to percolate 40 at gallons per hour. I have installed about 40 holes, so it takes about 15 minutes to distribute 40 gallons of water.
The flexible irrigation pipe is exposed for testing purposes. When testing is completed the hose will be buried and mulch or gravel will be inserted around all the outlet holes near the plants.
Cost
The cost of the project has been about $200 in materials. It took a few days to install.
Other Considerations
I have not yet installed either a bypass valve or an overflow for the system. These matters concern me and I will be addressing them. The main problem with the bypass valve is that I must install one that is electrically controlled as the place where the valve must be located is in the crawl space below the house. More on this later.
last modified 8/17/2014
Sunday, June 22, 2014
Cosmetics
As I have noted earlier, I have moved the filters so that they are located behind a stone wall. I have created a cavity with a material called Ditra that allows me to remove the upper pail for cleaning out the lower pail filter when necessary from time to time (I have not needed to clean it out yet, I will report on the frequency once I have some data on this.)
The sequence of pictures below are images of the filter behind the stone wall. The first is from a distance to show the camouflaged position. The others show progressively closer to see the details.
To see what the filters look like before I put them behind the wall please to to my post on the construction of the filters.
I have indicated elsewhere that I have excavated part of a hillside where I now have a level area to put the IBC Totes. This was done, primarily, to level the ground where the tanks are stored, but also to provide some level of cosmetic camouflage for the tanks. I have at this point constructed a perimeter wall on the uphill side of the tanks of hardy board and steel columns. I have backfilled the hill above the tank. This picture shows the tanks enclosed with the backfill above them. The white pipe is the overflow for when the totes are full to divert the water to the field below.
For the top of the tanks, since I have to protect them from light I am constructing a platform from pressure treated decking. I have decided to divide the platform into two parts so that if I need to service the tanks below it I can lift off the appropriate section. I am stapling a black landscaping fabric to the underside of the decking to keep light away from the tanks. I am also hinging the two sections of the deck together so that I can lift one section on top of the other should I need to service anything underneath.
I am also going to plant some bushes around the tanks to further camouflage the storage area.
last modified 8/15/2014
The sequence of pictures below are images of the filter behind the stone wall. The first is from a distance to show the camouflaged position. The others show progressively closer to see the details.
To see what the filters look like before I put them behind the wall please to to my post on the construction of the filters.
I have indicated elsewhere that I have excavated part of a hillside where I now have a level area to put the IBC Totes. This was done, primarily, to level the ground where the tanks are stored, but also to provide some level of cosmetic camouflage for the tanks. I have at this point constructed a perimeter wall on the uphill side of the tanks of hardy board and steel columns. I have backfilled the hill above the tank. This picture shows the tanks enclosed with the backfill above them. The white pipe is the overflow for when the totes are full to divert the water to the field below.
For the top of the tanks, since I have to protect them from light I am constructing a platform from pressure treated decking. I have decided to divide the platform into two parts so that if I need to service the tanks below it I can lift off the appropriate section. I am stapling a black landscaping fabric to the underside of the decking to keep light away from the tanks. I am also hinging the two sections of the deck together so that I can lift one section on top of the other should I need to service anything underneath.
I am also going to plant some bushes around the tanks to further camouflage the storage area.
last modified 8/15/2014
Friday, April 4, 2014
Backflow Prevention and Pressure Reduction
I have now spent some time looking at the situation I have and what I need to install: a backflow preventer and a pressure reducer.
The backflow preventer is required, because I am going to have my rainwater storage connected to the irrigation system, the irrigation system, in turn, is connected to my potable water system that is supplied by the municipal water district. I do not want non potable water (rainwater, in this case) to infiltrate either my potable water supply (domestic water for the house), or the municipal water supply system.
If I do not install such a device, and if the pressure reduces on the municipal system, for some reason beyond my control, and the water pressure is higher on the rainwater storage system side, then water could flow in the wrong direction and contaminate the public water supply and my domestic water supply.
The pressure reducer is needed to reduce the water pressure in the irrigation system from the nominal 50 psi pressure of the water coming from the municipal system to 30 psi for the irrigation system. There are a number of reasons to reduce the pressure.
The sprayers in my irrigation system were designed to optimally function at 30 psi. The spray heads will last longer, will distribute water in a more even pattern over their range, and it will most importantly, reduce misting which could waste as much at 40% of the water being used by having it carried off into the air.
Needless to say, the reduction in pressure will most likely reduce my water consumption (and water bill) by at least 25%. I may have to compensate for the lower pressure by leaving the spray head active during a given cycle by extending the time it is on.
There are many kinds of devices to accomplish these functions on the market, most are relatively expensive for their size, but cheap when it comes to their ROI. I will try to include here what I am finding and why I am choosing the specific devices.
There seem to be very specific instructions on where and how to install these devices. For example they must be located substantially above the ground (unless you go for a much more expensive device) and also be higher than the sprinkler heads.
The backflow preventer is required, because I am going to have my rainwater storage connected to the irrigation system, the irrigation system, in turn, is connected to my potable water system that is supplied by the municipal water district. I do not want non potable water (rainwater, in this case) to infiltrate either my potable water supply (domestic water for the house), or the municipal water supply system.
If I do not install such a device, and if the pressure reduces on the municipal system, for some reason beyond my control, and the water pressure is higher on the rainwater storage system side, then water could flow in the wrong direction and contaminate the public water supply and my domestic water supply.
The pressure reducer is needed to reduce the water pressure in the irrigation system from the nominal 50 psi pressure of the water coming from the municipal system to 30 psi for the irrigation system. There are a number of reasons to reduce the pressure.
The sprayers in my irrigation system were designed to optimally function at 30 psi. The spray heads will last longer, will distribute water in a more even pattern over their range, and it will most importantly, reduce misting which could waste as much at 40% of the water being used by having it carried off into the air.
Needless to say, the reduction in pressure will most likely reduce my water consumption (and water bill) by at least 25%. I may have to compensate for the lower pressure by leaving the spray head active during a given cycle by extending the time it is on.
There are many kinds of devices to accomplish these functions on the market, most are relatively expensive for their size, but cheap when it comes to their ROI. I will try to include here what I am finding and why I am choosing the specific devices.
There seem to be very specific instructions on where and how to install these devices. For example they must be located substantially above the ground (unless you go for a much more expensive device) and also be higher than the sprinkler heads.
Thursday, April 3, 2014
Installing a Valve to Divert the Rainwater to the Storage Tanks
On my house here there was a 4 inch drain pipe coming off each downspout that all collected (underground) into one pipe that was diverted out to the street. It was while I was putting on the deck to my house that I redid the piping for the downspouts. At one point just before the drainage for about half the house connected to the main line going out to the street, I installed a valve. The valve (all PVC) allows me to either have the rainwater go straight to the street, or, if I choose, go to my storage tanks. I purchased it here in town at one of the supply houses. It is a very simple device that is buried in the ground with a shaft that comes up to the ground level. When I want to divert the water to my tanks I merely turn the handle inside the shaft and I am done. The top of the shaft is level with the ground and is located in one of my flower beds. I have installed a plastic grate on top of the shaft (6") to protect the shaft from getting debris down in there. I really like the valve -- Cheap and effective.
Monday, March 31, 2014
Rainwater Harvesting Regulation
Now that I am harvesting rainwater, there is an app for that. Just kidding. Actually, there is a regulation for that.
As part of the CPC 2013 (California Plumbing Code). There are regulations and limits on rainwater catchment systems effective 1/1/2014.
First, the rainwater system must be isolated from the potable water supply, by either air, or a backflow prevention device. I intend to put a backflow prevention device in when I connect the storage tanks to the underground irrigation system, since the irrigation system is connected to the potable water supply.
Next, there seem to be restrictions on the ability to use the rainwater in a spray irrigation system. The concern here is to prevent pathogens from being released into the air where they might infect someone. There seems to be a workaround if the filtration level is sufficient. Apparently 100 micron filtration will do it. I am going to that level of filtration anyway to insure that I do not clog the spray heads of the irrigation system.
There is also a restriction on the maximum amount of storage in a tank. Apparently 5000 gallons is the maximum storage per tank without a building permit. Since I intend to pump the rainwater harvested back through my irrigation system and I intend to have more than 5000 gallons of storage, but not more than that in any one tank. For a citation on CPC 2013 requirements see this website.
After talking with the county building department I was informed that I must secure a plumbing permit at a nominal cost before I do the job. They have asked that I submit a plan to them for the project. I suppose I will print out many of the illustrations I have already made for this blog as part of the plan. Apparently I am the first person to even ask about this stuff. No one has sought a permit for this use previously.
April 3. Today, I had a building inspector here for the final inspection of my deck. I passed with flying colors. (After all, it was the installation of the deck that started me on this path. I rerouted the downspouts to the valve so that water could be diverted to the storage tanks.) He informed me that I should NOT file for a plumbing permit and that I should just put it in and not worry about it. Now I have an answer that I like. He confirmed that the restriction on 5000 gallons for a permit is per tank, not per system.
last modified 4/5/14
As part of the CPC 2013 (California Plumbing Code). There are regulations and limits on rainwater catchment systems effective 1/1/2014.
First, the rainwater system must be isolated from the potable water supply, by either air, or a backflow prevention device. I intend to put a backflow prevention device in when I connect the storage tanks to the underground irrigation system, since the irrigation system is connected to the potable water supply.
Next, there seem to be restrictions on the ability to use the rainwater in a spray irrigation system. The concern here is to prevent pathogens from being released into the air where they might infect someone. There seems to be a workaround if the filtration level is sufficient. Apparently 100 micron filtration will do it. I am going to that level of filtration anyway to insure that I do not clog the spray heads of the irrigation system.
There is also a restriction on the maximum amount of storage in a tank. Apparently 5000 gallons is the maximum storage per tank without a building permit. Since I intend to pump the rainwater harvested back through my irrigation system and I intend to have more than 5000 gallons of storage, but not more than that in any one tank. For a citation on CPC 2013 requirements see this website.
After talking with the county building department I was informed that I must secure a plumbing permit at a nominal cost before I do the job. They have asked that I submit a plan to them for the project. I suppose I will print out many of the illustrations I have already made for this blog as part of the plan. Apparently I am the first person to even ask about this stuff. No one has sought a permit for this use previously.
April 3. Today, I had a building inspector here for the final inspection of my deck. I passed with flying colors. (After all, it was the installation of the deck that started me on this path. I rerouted the downspouts to the valve so that water could be diverted to the storage tanks.) He informed me that I should NOT file for a plumbing permit and that I should just put it in and not worry about it. Now I have an answer that I like. He confirmed that the restriction on 5000 gallons for a permit is per tank, not per system.
last modified 4/5/14
Friday, March 28, 2014
Secondary Storage of Rainwater
I have designed, but not yet implemented the secondary storage array of IBC totes for the rainwater catchment system. See illustration below
This array or "wall" is for 15 IBC totes. Each tote has a 275 gallon capacity, so this array has a capacity of 4125 gallons. The wall is about 20 ft. long by 12 ft. high and 4 ft. deep. I will connect all tanks at the same level together with a valve to not permit the water to go down to the next lower level in order to keep the water as high as possible in the array for keeping the water pressure high at ground level.
It is my hope to construct two of these walls about 12 ft. apart, running parallel with each other giving me a total capacity of 8,250 gallons for the secondary storage. That way I can construct a roof over both and basically have a breezeway between the two for storage (I can even fit my car in that space). I am going to have to put some sort of cover over the wall to protect the tanks from the UV light.
I will have to modify this design if I use it to allow for air to vent out of the individual tanks as the water rises, just as I have done on the primary tanks. More on this later.
I have also learned of very inexpensive water bladders that will hold 10,000 to 40,0000 gallons of water that might be considerably less expensive, not require protection from the UV light since they are opaque black, and will pressurize as they fill to give me more water pressure without having to pump the water. More on this later.
last revised 6/17/2014
Pumping Water
I have to pump water in a variety of ways. First, I have to pump from the primary storage tanks to the secondary tanks. Additionally, in order to get the required pressure into the irrigation system I have to further boost the pressure of the water coming out of the secondary tanks going into the irrigation system to 30 PSI. In order to accomplish this I have installed pumps into the IBC tote and plumbed the line to the irrigation system. I have illustrated below the way I am arranging the pump.
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| Sump Pump before installation into the IBC Tote |
I have now installed and plumbed in the sump pump to remove water under pressure from the tanks. I have two ball valves in the line so that I can have the irrigation water line feed shut off and use the pump with the faucets in that section of the yard, or I can open the valve to the irrigation line and pump water into my irrigation system. Alternatively, I can run water directly from my irrigation system to my faucets by closing the valve to the tank. See illustration below.
last modified 6/20/2014
Thursday, March 27, 2014
Moving Rainwater to the Secondary Storage Area
I have placed the 4 IBC totes at a location slightly downhill from the house. This way the rainwater can gravity fill the totes. I am going to have to pump the water uphill to secondary storage tanks to get the pressure I need to operate the irrigation system. I need about 30 PSI pressure to operate the sprinklers and valves.
At first I thought I would put PVC tubing between the two areas. They are located about 300 ft. apart. Then, I came up with the idea to pump the water from the totes directly into the irrigation tubing, and then make a second splice into the same irrigation tubing closer to the secondary storage area and use the existing irrigation tubing to transport the water. This will save me tubing and trenching about 175 ft. of the 300 ft. distance. I will have to install either shut off valves at each end or put in a back flow preventer.
last modified 6/21/2014
At first I thought I would put PVC tubing between the two areas. They are located about 300 ft. apart. Then, I came up with the idea to pump the water from the totes directly into the irrigation tubing, and then make a second splice into the same irrigation tubing closer to the secondary storage area and use the existing irrigation tubing to transport the water. This will save me tubing and trenching about 175 ft. of the 300 ft. distance. I will have to install either shut off valves at each end or put in a back flow preventer.
last modified 6/21/2014
Filtration of the Rainwater before entry into the IBC Totes
My first attempt at filling the tank resulted in a lot of debris entering the tanks. I have cleaned the tanks and added a filtration system to the line before the water gets to the tanks. It seems to be working just fine.
I constructed the filter out of two 5 gallon plastic container pails, one on top of the other.
The top pail has a very course plastic mesh to filter out leaves and other very large debris. Immediately below that I used a screen mesh (window screen material). I put holes in the bottom of the center of the first pail to allow the water to pass into the second pail. The second pail is constructed with a toilet flange on the bottom to allow drain pipe to be attached to bring the water to the IBC tote, above the flange in the pail I have a stainless steel waste can that has a landscape fabric sock that is fitted inside the stainless steel waste can. The most frequent maintenance is the cleaning out of the first strainer. That strainer got real clogged during the first rain of the season when all the debris on the roof was washed off. After that initial cleaning it has not required much maintenance.
Finally, I have purchased a commercial 100 micron 32" x 7" nylon filter sock to insert into the opening of the IBC tote to catch any impurities that the other two filters did not get. I got this filter from filtersfast.com. It is Pentek NMO100P2S Bag Filter.
As an added protection to the system I have added a small amount of chlorine to the tanks to kill off any nasty organisms that may have been present. I do not have a schedule for doing this on a regular basis. I know that plants do not like the chlorine, so I will keep a close eye on what is going on in the tanks.
March 31, 2014. It is raining again today. I noticed that the filter was clogged. I have discovered that the grit (sand) from the roof that is coming into the system is forming a layer of sediment on top of the screen on the bottom of the upper pail. There were practically no leaves in the upper basket/strainer in this pail. I am now installing a second screen into the upper basket/strainer such that the screen goes up the walls of the basket/strainer. This way, if the sediment covers the bottom of the basket the water can still get out the sides and still be filtered. Hopefully this modification will solve the problem. See improved schematic for the upper pail (below):
last modified 4/14/2014
I constructed the filter out of two 5 gallon plastic container pails, one on top of the other.
The top pail has a very course plastic mesh to filter out leaves and other very large debris. Immediately below that I used a screen mesh (window screen material). I put holes in the bottom of the center of the first pail to allow the water to pass into the second pail. The second pail is constructed with a toilet flange on the bottom to allow drain pipe to be attached to bring the water to the IBC tote, above the flange in the pail I have a stainless steel waste can that has a landscape fabric sock that is fitted inside the stainless steel waste can. The most frequent maintenance is the cleaning out of the first strainer. That strainer got real clogged during the first rain of the season when all the debris on the roof was washed off. After that initial cleaning it has not required much maintenance.
Finally, I have purchased a commercial 100 micron 32" x 7" nylon filter sock to insert into the opening of the IBC tote to catch any impurities that the other two filters did not get. I got this filter from filtersfast.com. It is Pentek NMO100P2S Bag Filter.
As an added protection to the system I have added a small amount of chlorine to the tanks to kill off any nasty organisms that may have been present. I do not have a schedule for doing this on a regular basis. I know that plants do not like the chlorine, so I will keep a close eye on what is going on in the tanks.
March 31, 2014. It is raining again today. I noticed that the filter was clogged. I have discovered that the grit (sand) from the roof that is coming into the system is forming a layer of sediment on top of the screen on the bottom of the upper pail. There were practically no leaves in the upper basket/strainer in this pail. I am now installing a second screen into the upper basket/strainer such that the screen goes up the walls of the basket/strainer. This way, if the sediment covers the bottom of the basket the water can still get out the sides and still be filtered. Hopefully this modification will solve the problem. See improved schematic for the upper pail (below):
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| Improved Upper Pail Schematic |
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| Photo of two pails before being camouflaged. |
last modified 4/14/2014
Rainwater Storage - IBC Totes
I have stumbled onto IBC Totes (see picture above). These are Intermediate Bulk Containers (IBC) that are used in the commercial trade for the storage and transport of liquid, both food grade and otherwise. I am not an expert on these things, so if I make some mistake about them I will stand corrected if anyone wishes to point it out to me.
These totes are almost cube shaped and look like a commercial storage unit on a palette. They are approximately 4' X 4' X 4' depending upon their capacity. (250, 275, or 330 gallons) The larger capacity totes are taller. They allow for a fork lift to move them around and they have a pallet skid built into their bottoms. They are made of polyethylene and have a galvanized metal skeleton to hold it all together and give the thing strength. They can be stacked on top of each other quite safely, but I think, fully loaded with water, they would be limited to 3 high, with the most elevated tote only about 2/3 full. They have an opening on top that has a 6" screw lid. The lid has a removable 2" plug in its center that can be removed to insert a threaded 2" nipple or pipe.
At the base there is a 2" male threaded opening that is controlled by a ball valve.
These IBC totes are readily available and inexpensive to purchase. I have purchased 4 of the 275 gallon variety and paid $100. each for them. They weigh about 120 lbs. each and can be rolled around easily by one person. I might have difficulty stacking them on top of each other by myself.
I have plumbed the 4 units I purchased together with 2" PVC and appropriate elbows and tees at the output at the bottom of the tanks so that the tanks are all interconnected with each other. So, when I fill or remove water from one unit the water level will raise or lower in all the units. I have also put a faucet on the piping so that I may remove the liquid (see Top View illustration below)
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| Top View |
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| Front View |
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| Photo of my four primary tanks plumbed together with a hose spigot on the end. |
There are a few problems with just putting the tanks together and leaving them out in the sun. Since they are translucent plastic it is my understanding that the plastic will deteriorate from the ultraviolet light and that the water inside would grow algae if it is left in the light. So I am interpreting this to mean that I must build some sort of enclosure to block the light from the tanks.
I have also brought a drain line from the downspouts from my roof through the filter to the top opening of one of the tanks to fill the tanks. I have discovered that I must leave the caps on the tanks loose so that air can enter and escape from each tank for the water to move freely between the tanks. So, I have redesigned this part. I have constructed a manifold (see diagram below) with the 4" drainpipe coming in and using 4" x 2" Tees (one for each of the three tanks, except the one with the pump coming out). Since the tanks are interconnected by the plumbing at the bottom, the remaining tank will fill by leveling with the others. I changed the design to allow for air to escape from the tanks, allowing the water to rise in the tanks easily.
The overflow output is constructed so that it is just slightly higher than the input to the tanks. That way, once the tanks are full the water level in the drain will rise and exit out the overflow line and be directed to a gravel pit I have constructed to catch this water and not erode the soil.
last modified 6/16/2014/2014
History of Water Consumption, Water Production, and ROI Analysis
The table below is an adjusted version of my water consumption for the last five years (units are in CCU Ft. [CCU = hundreds of cubic feet]). I say adjusted because there have been a number of notable events that have occurred which have distorted the "real" usage. We had a malfunction in 2011 when we were in Europe for two months which caused excessive watering, and we had a "blow-out" in our system caused by excessive water pressure in 2010. In both instances the water company has "adjusted" our usage as an accommodation. Yellow highlight in the chart below are readings since I started water conservation efforts
Jan-Feb Mar-Apr May-Jun Jul-Aug Sep-Oct Nov-Dec Total
2014 32 10 78 79 77 13 289
2013 7 31 113 117 95 43 406
2012 9 14 83 116 84 14 320
2011 8 9 84 93 90 33 317
2010 5 6 69 89 89 26 284
2009 8 20 89 82 121 6 326
Avg. 11.5 15.0 86.0 96.0 92.4 22.5 323.7
What is not reflected in the table above is a leak that developed starting in about April, 2013 and lasted until January, 2014.
I have created a further nominally adjusted water usage for the last five years reflecting this additional leak as follows:
Jan-Feb Mar-Apr May-Jun Jul-Aug Sep-Oct Nov-Dec Yearly
2014 8 10 78 79 77 13 265
2013 7 10 83 93 87 22 302
2012 9 14 83 116 84 14 320
2011 8 9 84 93 90 33 317
2010 5 6 69 89 89 26 284
2009 8 20 89 82 121 6 326
Avg. 7.5 11.5 81.0 92.0 91.3 19.0 302.3
This next table is the same as above with projected numbers in red and the tier level in either Blue, Green, Orange, or Yellow corresponding to I, II, III, IV.
Jan-Feb Mar-Apr May-Jun Jul-Aug Sep-Oct Nov-Dec Total
2015 5 6 70 70 70 10 231
2014 8 10 78 79 77 13 265
2013 7 10 83 93 87 22 302
2012 9 14 83 116 84 14 320
2011 8 9 84 93 90 33 317
2010 5 6 69 89 89 26 284
2009 8 20 89 82 121 6 326
Avg. 7.5 11.5 81.0 92.0 91.3 19.0 302.3
2013 2013 2013 2013
Actual RED Total % by volume cost % by cost
Tier I BLUE 116 38.41% $387.44 16.14%
Tier II GREEN 103 34.11 770.44 32.10%
Tier III ORANGE 83 27.48 1,242.51 51.76%
Tier IV YELLOW 0 0.00 0.00 0.00%
Total 302 100.00 2,400.39 100%
Below are the actual 2014 water consumption numbers.
2014 2014 2014 2014
Projected RED Total % by volume cost % by cost
Tier I BLUE 109 41.13% $407.66 20.37%
Tier II GREEN 99 37.36 740.52 37.00%
Tier III ORANGE 57 21.51 853.29 42.63%
Tier IV YELLOW 0 0.00 0.00 0.00%
Total 265 100.00% 2,001.47 100.00%
Below is the actual difference between 2013 and 2014.
Difference 2013 - 2014
Projected RED Total % by volume cost % by cost
Tier I BLUE 7 -2.72% $-20.22 -4.23%
Tier II GREEN 4 -3.25 29.92 -4.90%
Tier III ORANGE 26 5.97 389.22 9.13%
Tier IV YELLOW 0 0.00 0.00 0.00%
Total 35 398.92
I started daily monitoring of the water consumption on February 1, and will keep a current log on-line on a bi-monthly basis starting with the March/April usage.
Note that all tier III water is used during the 6 month period from May to October. Further note that for 2013 while only 27.48% of the volume of water is from Tier III, 51.76% of the cost is attributable to this use. This is a total of 83 CCU of water, approximately 62,000 gallons of water during the 6 month period.
I understand that by reducing the water pressure from 50 lbs. to 30 lbs. will make the sprinklers operate more efficiently and reduce the misting and evaporation of water by at least 25%. This would reduce the water need to about 46,000 gallons.
It is my hope that I will be able to use the stored rainwater that exists in the tanks starting on April 13 of each year to offset this Tier III water use. I think that having the tanks full on that date will not be difficult to achieve.
I estimate that I water the landscape about twice a week, or 18 times per bimonthly period. I will deal with conservation of water use elsewhere. Each cycle is about 3,500 gallons, which comes to about 64,000 gallons. Of these 64,000 gallons 59 CCU or 44,100 gallons are Tier I and Tier II water, leaving about 20,000 gallons of Tier III water to conserve for each bimonthly period. With 10,000 gallons in storage at the beginning the summer season (April 13) and some additional rainwater (computations on precipitation to gallons of storage is below) it is hoped that I can accumulate the additional water needed to eliminate entirely the need for all Tier III water.
I list below monthly averages for high and low temperatures and precipitation.
Month Avg. Avg. Mean Avg. Record Record
High Low Precip. High Low
| Jan | 54°F | 42°F | 48°F | 6.95 in. | 82°F (1962) | 26°F (1949) |
| Feb | 59°F | 44°F | 52°F | 7.32 in. | 80°F (1964) | 26°F (1989) |
| Mar | 63°F | 45°F | 54°F | 4.59 in. | 88°F (1952) | 24°F (1977) |
| Apr | 67°F | 47°F | 57°F | 1.91 in. | 92°F (1996) | 29°F (1976) |
| May | 71°F | 50°F | 61°F | 0.89 in. | 100°F (1976) | 31°F (1976) |
| Jun | 76°F | 53°F | 65°F | 0.14 in. | 110°F (1961) | 40°F (1976) |
| Jul | 80°F | 55°F | 68°F | 0.00 in. | 109°F (1972) | 34°F (1975) |
| Aug | 80°F | 55°F | 68°F | 0.05 in. | 105°F (1998) | 41°F (1996) |
| Sep | 79°F | 54°F | 67°F | 0.21 in. | 109°F (1958) | 40°F (1985) |
| Oct | 73°F | 51°F | 62°F | 1.49 in. | 106°F (1980) | 34°F (1974) |
| Nov | 62°F | 46°F | 54°F | 4.31 in. | 88°F (1980) | 30°F (1974) |
| Dec | 54°F | 42°F | 48°F | 7.59 in. | 79°F (1967) | 20°F (1990) |
Total total annual Rainfall 35.35 in.
I am now tracking actual precipitation by week for 2014.
Jan 1 0.0
Jan 8 0.0
Jan 15 0.0
Jan 22 0.0
Jan 29 0.0
Feb 5 0.7
Feb 12 0.38
Feb 19 0.0
Feb 26 0.84
Mar 5 0.14
Mar 12 0.0
Mar 19 0.05
Mar 26 0.44
Apr 2
My measurement of precipitation to gallons of water harvested is estimated to be approximately 1,000 gallons for each inch of rain. Right now I am only harvesting the rain from about half my roof. Since my house footprint is 3,200 sq. ft. I estimate that 1,600 sq. ft. of footprint (half) is yielding the 1,000 gallons of water. To cross check this number, each foot of roof footprint is generating 7.48/12 = .623 gallons of water for each inch of rain, and .623 gallons x 1,600 sq. ft. = 1,000 gallons of water generated for an inch of rain.
The table below recapitulates the rainfall for the 6 summer months categorized into bimonthly pairs corresponding to the bimonthly billing periods.
Computation of Rainwater Collected Per Inch of Water for Summer Months
Period Estimated Potential Potential
Precipitation Rain Harvest Rain Harvest
(in inches) Half Roof Full Roof
(in gallons) (in gallons)
May - Jun 1.78 1,780 3,560
Jul - Aug .16 160 320
Sep - Oct .99 990 1,980
Totals 2.93 2,930 5,860
Even if I could capture every gallon of water generated during this period of time for the entire roof, with a storage capacity of 10,000 gallons I would only be capturing 10,000 gallons prior to April 12, and 5,860 gallons after April 13, for a total of 15,860 gallons. The Tier III demand is 20,000 gallons per bimonthly period for three periods, or 46,000 gallons. So, we have a deficit of 30,140 gallons. The only way to improve this situation is to increase the storage capacity so that by April 13, there is more water stored, or to reduce the demand by further conservation techniques.
On the bright side, the reduction to 30,140 gallons of Tier III water will save approximately $603.40 on the water bill, but only $317.48 is attributable to the water storage and the remainder to the pressure reduction.
The cost of 1,100 gallons of water storage is approximately $300, or $0.27 per gallon. 10,000 gallons will cost approximately $2,700. So, the anticipated return on investment (ROI) on $2,700 will be $317.48 per year less $130 for depreciation and maintenance, or $187.28 net, and a 6.9% (ROI) on an average year. I can only assume that the cost of water will continue to rise, while the cost for the storage system will be a sunk cost.
The ROI on the pressure reduction regulator is much higher, probably paying for itself in less than one year. I found one for under $100, but have not installed it yet.
last modified 10/16/2014
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