Collect Rainwater for
Irrigation
Collect rainwater
with rain barrels at each rainwater leader or downspout. The collected
rain displaces potable water otherwise wasted for irrigation.
Most roofing
materials are suitable for rainwater collection, except for redwood,
cedar or treated wood shingles and shakes, which may contaminate
water and soil by leaching toxic materials when wet. Check with
local authorities before using rainwater from these types of roofing
materials to water fruit- or vegetable- producing plants.
Manufactured
rain barrels are widely available in sizes that range from 36 to
75 gallons. Rain barrels are also easily made from commercial plastic
barrels; recycled food-grade PVC barrels are often available free.
The larger the container, the more potable water will be saved,
but it is rarely economic to store sufficient water for an entire
summer.
Rain barrels
should incorporate a “roof washer” or “first flush”
device, to avoid storing water contaminated with bird droppings
and dust. They should also incorporate an inlet screen and an overflow
outlet. Overflow and drain valves should include hose couplings,
and discharge at least 6 ft. from foundations.
Cautions
- Ensure that
"flat" roofs have sufficient slope to drain completely,
without long-term ponding.
- Avoid using
rainwater collected from asphalt roofing, cedar or treated shingles
for food gardens.
- Ensure that
rain barrels include first-flush devices to avoid water contamination.
