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Thursday, March 27, 2014

Rainwater Storage - IBC Totes

I have searched for economical water storage tanks and have been surprised, for the amount of water I want to store, how expensive they can be, and how difficult they are to set up and move into place.

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)

Top View

Front View
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

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