Water Harvesting on the Farm
By Rich Casale, USDA Natural Resources Conservation Service
richard.casale@ca.usda.gov; 831-475-1967
Background/Introduction
Rainwater harvesting is not a new concept. In fact it is an ancient technique. Archeologists have dated
harvesting systems back at least 4000 years and suspect that the Chinese were using the concept more
than 6000 years ago. Rainwater has long been regarded and desired for its purity, softness and nearly
neutral ph. Cisterns built 2000 years BC in Israel are still to this day storing water!
Need and Purpose
The conservation of water supplies has never been more important than now with groundwater aquifers
in severe overdraft, seawater intrusion, extended drought and higher energy use and costs related to
extracting water from the ground. Water harvesting developments can serve one or more of the
following uses: Agricultural irrigation, wildlife water, landscape plantings, hedgerows, cover crops,
critical area or wildlife plantings, fire protection, home gardens, wash water and dust control, sediment
and contaminant collection, water quality protection, detention (to meter and control runoff and
erosion), and multiple purpose.
Sources of Water (including where water is stored in the landscape)
Irrigation tail water, storm water runoff, springs, groundwater aquifers, rivers and streams, ponds and
reservoirs, water in the soil in the form of perched or high water table, wetlands, snow packs, flood
plains, direct rainfall, condensation inside green and hoop houses, dew, urban related runoff, waste
water recycled treated water and sea water. Note: One inch of rain falling on 1500 square feet of
impervious surface (roof top) yields approximately 1000 gallons of water!
Systems Types
There is a wide variety of water harvesting system designs are available for roofs (homes, buildings,
etc.), roadways and parking areas, greenhouses and hoop houses, landscape & other places where
water can be harvested.
Harvesting Approaches (other than pumping from a water well)
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Spring Development
Captured landscape storm water and irrigation runoff - Bio-swales, Wetlands, Drainage Ditches
and Canals, Ponds and Reservoirs, Cisterns, etc.
Water catchment from impervious surfaces (roof tops, etc.) with tank and/or lined pond storage
including gutters, drains, pipeline infrastructure, etc.
Waterway/Stream Diversions
Subsurface Drainage Collection galleries or subsurface drains outlets including “drywells”,
ponds, wetlands, etc.
Desalination
Purification/treatment of captured waste and tainted subsurface drainage, irrigation and storm
water runoff and other impure sources of water.
Components of a Water Harvesting Catchment/Recovery/Recycling System
Holding tanks, tank vents and screens, first flush devices, faucets or valves, pond(s), pond liner, cistern,
catchment surface, gravity system and/or pumping plant(s), roof runoff structures (gutters and down
drains), filtration/treatment/purification systems (if necessary), spillway pipe/overflow device(s) (with
outlet protection), delivery/conveyance pipelines, diversions, lined ditches, underground pipe outlets,
spring box, subsurface drains and related fixtures.
Companion Practices to a Water Harvesting System
Fencing (for pond safety); vegetative plantings for critical area treatment, screening, water treatment
areas and wildlife; irrigation water management; flow/water meter; float value; irrigation pipeline and
irrigation system; pump; electrical supply; fish and wildlife structure; structure for water control
(velocity dissipater); surface drainage; & operation & maintenance.
Some Advantages/Benefits of Rainwater Harvesting
Rainwater comes without charge, its sodium free and superior for crops and landscape irrigation.
Harvested water is close to the source eliminating the need for costly distribution systems. Harvesting
rainwater and other water found on the landscape provides a water source when groundwater is
unacceptable or unavailable and/or helps augment limited groundwater supplies.
Zero hardness prevents scale on equipment, appliances and the need for water softeners.
Rainwater harvesting reduces storm water runoff reducing likelihood of soil erosion and pollution. It can
also help to reduce the use of energy and cut utility bills.
Find Out More
Contact the USDA Natural Resources Conservation Service at: www.ca.usda.nrcs.gov
NRCS is an equal opportunity employer and provider
“Helping People Help the Land”