1000 Gallon Rainwater Collection and Irrigation Pump System

Due to the drought conditions here in California I decided to install a rainwater collection system to capture rain water from our roof.

Here are the primary components that I ended up installing:

1. 1000 gallon plastic water tank. They come in multiple shapes and sizes to fit your space best. An underground ‘cistern’ would have been my first choice but that would require digging a big hole which I was not prepared to do. Maybe an upgrade down the road someday..

2. Roof runoff downspout diversion PVC pipes – most people recommend 3″ pipe, but I used 2″ and it seems to be working fine. Just make sure it is UV resistant.

3. 12 volt water pump for irrigation distribution. I went with a SHURflo 4008-101-E65 3.0 Revolution Water Pump and it has been working well for several months now. The pump is strong enough to activate 1/4″ irrigation sprayers in a garden bed about 70′ away via 3/4″ PVC then 5/8″ then 1/4″ irrigation poly tubing. It only runs when the irrigation valve opens up and the pressure drops in the pipe. Then it shuts off when the valve closes and the pressure builds up again in the pipe. The pressure required to run/stop is adjustable on the pump via an allen key. I disconnected the pump from the battery after the tank was dry to prevent it from running. I used the SHURflo 94-591-01 Pump Silencing Kit to make it easier to connect my PVC irrigation pipes to the pump, as well as this water filter that catches any debris coming out of the tank before it goes into the pump and on to the irrigation system.

4. Solar panel and battery to run water pump. I am using a Go Power! GP-SF-5 SUNfilm 5 Watt Solar Panel and it is working great to charge the UPG 85980/D5722 Sealed Lead Acid Battery that I am purchased for this purpose. The solar panel has a built in sensor that prevents it from overcharging or draining the battery so it’s a simple set up w/ no additional accessories needed.

5. Secondary collection location with Wayne Water Systems VIP50 1/2 HP 2,500 GPH Submersible Utility Water Pump to send water to main tank (runoff from other side of the roof). This pump is strong enough to pump water up and over our roof which is about 14′ at the highest point. The sump pump has a float attached to it that switches it on when the can fills up with water and shuts it off when it has been pumped out.

6. PVC Ball Valve to switch irrigation system between city water and water tank for when the tank runs dry. I recommend slip joints and PVC glue over threaded joints which tend to often leak.

7. Downspout First Flush Diverter to keep dirty rain water that carries dust off of the roof at the beginning of each rainfall. You have to purchase a length of 4″ PVC that suits your location as your first flush reservoir.  there is a ball inside that floats up and plugs it when it is full which then sends the clean water into the tank. It comes with a drip valve that goes on the bottom of the reservoir which slowly drains it between each rain. It can also be drained manually by unscrewing the plug at the bottom.

One of the biggest challenges was getting the huge water tank over the fence into the back yard – I ended up using a cheap block and tackle system leveraged from a temporary 20 foot 2×4 ‘crane’ which allowed me to do this by myself.

The pictures below tell most of the story.

The tank took about three days of consistent rain to fill up completely, and the full tank lasted for about three months of almost daily watering of three 4′ x 12′ raised garden beds.

We had an early day of rain in September that filled the dry tank up a little and all I had to do was connect the pump and switch the water line valve to draw from the tank and we’re back on rainwater irrigation for a few more weeks.

It will take a long time for the system to pay for itself – but it is a fun project and helps with the drought, and rainwater is better for garden veggies than city water which contains chemicals like chloride, fluoride, chloramine, etc.