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.