Posted on: Monday, May 30, 2005

By Jan TenBruggencate
Advertiser Science Writer

Rainwater pours off the roof, across the yard and off the property.

Some of it soaks in, some evaporates, but much washes away, lost to residents who still pay for municipal water for irrigation and other purposes.

In many rural areas, particularly on the Big Island, homeowners without access to municipal water use catchment systems, retaining rain that falls on the roof in large tanks. But there's a place for small rainwater systems even if you live in the suburbs and have piped-in water.

"It saves money and saves water. We live on an island and there's only so much fresh water to go around," said Jon Abbott of The Green House, a sustainability education organization in Pauoa Valley. Abbott, who offers workshops on making rain barrels, said he likes to use rainwater to irrigate plants.

It doesn't take much rain to add up to a lot of water. Even a modest Hawai'i home with a roof covering 1,000 square feet will fill 11 55-gallon drums in a 1-inch rainfall.

Rainwater is low in minerals and the chlorine used to disinfect water supplies. But it can be contaminated by roofing materials and by leaves and other organic material in gutters and drainpipes. So generally, it can be good for watering the garden but shouldn't be used for drinking without proper filtration and disinfection.

The simplest collection system might use the gutters and downspouts already present on a home to direct water into a tank or barrel. You can build tanks, buy them or find one you can recycle, but be careful about what has been in it before. A tap near the bottom of the tank can be convenient. Barrels also can be attached to pumps and PVC pipes to carry water to landscaping.

If looks matter, there are plastic rain barrels that resemble terra cotta, and one Web site was offering a 53-gallon white oak barrel recycled from Jack Daniels whiskey barrels. Online prices range from $100 to $200.

Don't forget to keep tanks covered or screened to avoid creating a mosquito problem. There are also risks of drowning if small children can get at open water tanks.

If you don't want a barrel or tank, there are downspout attachments that divert rainwater to a garden hose.

Find more information on the Web at www.rainbarrelguide.com. The University of Hawai'i's Web site on catchment water systems has information on how to get a brochure on the topic at www.ctahr.hawaii.edu/ctahr2001/CTAHRInAction/Feb_02/TMacomber.html.

Abbott can be reached at 988-8614.

If you have a question or concern about the Hawaiian environment, drop a note to Jan TenBruggencate at P.O. Box 524, Lihu'e, HI 96766 or jant@honoluluadvertiser.com; or call (808) 245-3074.