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Rainwater Harvesting (RWH)

Overview

The Rainwater Harvesting System is installed in the yard to the South of the house, between the concrete path and the evergreen Carolina fir, in December 2010. It comprises:
  • Four (4) 1,700-gallon subterranean cisterns connected by 1" PVC conduit approximately 1 foot above the bottom of the tank. Each cistern's dimensions are 11'L x 4.5'W x 5.5'H, inserted along their length, and configured in parallel in a ditch approximately 20'L x 7'D x 13'W.

  • The cisterns are fed by six (6) drainspouts from a 3,500 square foot roof, producing approximately 30,000 gallons of rainwater per year at current annual rainfall levels. The drainspouts convey the water via 3" ABS pipe into a Technik VF1 Volume Filter, mounted in a small culvert, to capture sediment.

  • The VF1 filter delivers clean water to the cisterns. Excess capacity/overflow runs off into the culvert.

  • The cistern furthest to the southwest contains a Divertron X-1200 submersible pump that activates (ON) automatically when water pressure drops in any of the four delivery conduits: Drip irrigation, pond water supply, hose bibb and domestic potable water. The pump turns OFF automatically when water level in the cisterns drops to the top of the pump.

  • The culvert contains a 1 HP sump pump to extract available water from a river/lake of storm and other runoff @ 5-6 feet underground to supplement rainwater collected in the cisterns. The pump turns ON automatically when the water level in the cisterns drops to 1/3 of cistern capacity. The pump turns OFF automatically whenever the cistern is either 2/3 full or the culvert's water is at too low a level.

  • A 50-gallon rain barrel stores up to 40 gallons of grey water collected from pre-warmed shower water for emergency use in case of a major earthquake. Grey water in excess of 40 gallons flows automatically into the cisterns via the rainspout conduits.
An electrical system powers the RWH pumps from the 200 Amp breaker panel mounted on the north side of the house. Two switches mounted on the west side of the house allow manual override of both pumps by turning either pump OFF as needed.

The drip irrigation and pond supply system supplies drip irrigation to the house's borders and individual vegetation.

RWH Distribution: Yard ( Non-potable )

RWH water is distributed via a 4-way manifold next to the hose bibb, for 4 applications:
  • Drip Irrigation: 3/4" conduit to two (2) valves, controlled by an Irritrol Rainbird automatic irrigation controller mounted on the South wall of the house. The controller is programmed to turn on the valves at 4 a.m. 3 days a week. The valves supply RWH via rubber tubing to:
    • Plant borders on the West, South and East sides of the house

    • Free-standing vegetation in the yard: birch grove, pomegranate, newly-planted redwood tree ( irrigation to be discontinued when the tree's roots are long enough to reach groundwater in the underground river at 5' ), a potato vine and a French Broom.

  • Pond - a 3/4" conduit to the pond maintains a steady pond water level, controlled by a float valve. The cistern's submersible pump activates when the pond water level drops.

  • Garden hose bibb - a 3/4" conduit to the bibb supplies RWH water to the hose whenever the bibb faucet is turned on.

  • Conduit - A 3/4 " conduit from the manifold around the South and East of the house to the garage for water purification and use inside the house ( see below ).

These applications have eliminated our monthly water bill and city-provided water, from 5 CCF (cubic feet) per month to zero. We pay only a monthly charge for the water meter. Rainwater now provides the entire 5 CCF, equivalent to nearly 4,000 gallons per month, or about 125 gallons a day.

RWH Distribution: House ( Potable )

The 3/4" pipe from the manifold (next to the hose bibb) around the corner of the house to the South side of the garage supplies cistern water for:
  • Water treatment and filtration.

  • Potable water within the house for shower, sinks, toilets and clothes washer.
The potable water distribution system is described Potable Water section.

Suppliers

Equipment & Service Vendor & URL
Cistern Suppliers RainHarvest Systems, Cumming, GA
Norwesco, Hanford, CA
Plastic-Mart
Pumps & Filters RainHarvest Systems, Cumming, GA
Massca Products, Winnetka, CA
Irrigation ControlIrritrol
InstallerOrozco Landscaping, Sunnyvale, CA
Cell: 408.898-6386

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