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Sun, Mar 6
7:30 am

Building a Rainwater Collection System- About two years after the house was completed, I decided to put in rainwater collection for the few days in the desert that we actually have rain. As with everything, I wanted to keep it inexpensive and do the labor myself. I went to the closest home improvement store and bought brown guttering to match the fascia and looked up instructions on how to gutter a house in one of the how-to books I had bought during construction. That was pretty easy - I have a fairly long house, so I decided to put a rainwater tank on either end of the house and slope the gutters from the middle of the house out to each end. I think calculating the slope, so it ended up right was the trickiest.

I learned from another green-minded friend, a trick about how to keep some of the dirty water out of the tanks. Instead of having the gutter downspout go directly into the tanks, the downspout branches and one part goes straight down for about two feet, then ends. The end has a rubber cap on it with a small hole. So, the first dirty water off the roof goes straight down into this tube. When the tube is full, the water then begins to travel horizontally into the rainwater tank. If your tank is below ground, then you can just make a short horizontal run of the downspout before it dips down into your tank. Here is a photo from one side of my house with the downspout and the horizontal tube running into the tank that is behind the orange door.

For tanks, I phoned a man that I heard about who sold rainwater tanks made from big cistern pipes. You just had to cement the pipe into the ground and he had a gauge out the outside to show the water level plus a hose connector. This was probably about 2005, before green was very popular. Anway, I left him a message and got a pretty funny, drunken voice mal back that he was no longer in the rainwater tank business and he'd rather get divorced again than start selling rainwater tanks. He did, however, point me to a company that sold large plastic tanks, so I went there. If you are considering this before you built your house, or with time to bring a large underground tank to your house, then by all means do this. I hear some of the least expensive rainwater collection tanks are (new) septic tanks underground. I was too late to do that, so I purchase two 500 gallon upright tanks. I had this feeling that if the tanks were upright, I'd have enough gravity pressure to push the water into my garden drip system. I rented a pickup truck for a day and hauled both tanks up to the house. They were light and opaque, so I could see the water level in them. Here is the one behind the door, that is half full of water. The other is in the lattice area on the west side of the house.

I only wanted to use rainwater on the garden. I grow vegetables and I am establishing trees around the property. I also have some low-water use plants, such as agave. They just need a little more than the desert offers. I did the math and realized that the tank would have to sit on a 50' hill in order to push the water up to 25 psi, which is what my drip system required. So, I went in search of a pump to increase the water pressure. After phoning all over and searching the web, I came up with an RV water pump that would turn on only when the drip system ran and would be okay if it ran dry. Here is a photo of the pump plumbed into pvc that runs from the base of the rainwater tank. I have manual valves that turn on the county water or the rainwater tank when it is full. These pumps cost about $150 and I got them at an RV supply store. They are made for solar electric, also.

The pumps have run for about five years now and been wonderful! One of them started to leak once and JJ took it apart, to find its gears full of gravel, so I put window screen over the top of the tanks to do a finer filter. I think the tanks cost about $300 each and with two pumps plus gutters, I spent about $1000 on this whole system. Hope this helps you and let me know if you have questions.

Keep it Simple - and be kind!