Site location:
Berkeley, CA

Backyard Cistern

  • Goals: To collect rainwater for outside irrigation.
  • Site description: A new roof was added to cover a patio area using plastic laminate. Gutters were added to this roof and directed into the cistern. The site has a second cistern collecting water from a different portion of the houses roof.
  • Cost: Cistern-$240 from Tank Depot and $80 in shipping (2 tanks were shipped together). Also required: strainer basket, top intake fitting, 4” plastic drainage pipe running up to the gutters and for the first flush diverter, faucet at the bottom of the diverter. Fittings and reducers for the bottom-of-tank outlet, shutoff valve, hose fitting (minimum). Costing another $100 for these various pipes and fittings. Total around- $420
  • System designer: home owner

System Description:


Dripping faucet releases 1st flush rainwater

Dripping faucet releases 1st flush rainwater

The gutters were routed from the new roof. A “first flush” system was installed by adding a Tee with a run of pipe going to the ground. The dirtiest first rainwater falls into this pipe and prevents it from entering the storage tank.

The first flush water is released at the bottom of the tube, either by opening the faucet completely, or by leaving the faucet open to a drip to slowly release the water.




RWcistern-tankThe 500 gallon cistern is located on a patio near the garden.








A screen inside the cistern keeps out leaves and other debris.






A garden hose is connected to the base of the cistern, rainwater is used for outside irrigation.   




    • Specifications and Notes: When the cistern was full there was enough pressure coming out of the hose (a soaker hose was used), but when it emptied the pressure dropped. A pump was installed in one tank to increase pressure into the hose. System owner says: What I learned: 500 gallons fills up quickly but also empties quickly. When I have more time I want to double the capacity.
    • Maintenance and trouble shooting: Check screens, empty first flush system after first rain.