Using Rainwater –

Posted by 13 Nov, 2012

Using Rainwater

Those of us who live in cities and towns, and eat food grown on industrial farms, depend on imported water for daily survival. Our water travels hundreds of miles to reach us. It is powered by mountain-leveling coal, mega-dam hydro-power, and nuclear power. The infrastructure that brings us this water costs billions of dollars in public tax money and household utility bills.
Harvesting rainwater can reduce our need for water transport systems that threaten the health of the water cycle and our local environments. Ironically, water use is often highest in the places where rain falls the least. But whether you live in the damp Pacific Northwest, the arid Mojave desert, the thunderstorm Midwest, or beyond, you depend on problematic water infrastructures.

Rainwater harvesting is one strategy to reduce domestic water use. Harvesting rainwater and dozens of other green household practices can bring us greater sustainability. Growing plants that shade and installing insulated windows can reduce energy use. Increasing home food production reduces demand for wasteful water use in industrial fields. Above all, rainwater harvesting increases quality of life: ours, and that of life around the world.
In arid climates and places with salty irrigation water, rainwater flushes salts and chemicals out, increasing health and soil vitality.
Design landscape to welcome the rain

On any house lot, there are three potential ways to harvest the rain: direct rainfall, street harvesting, and roof harvesting.
The easiest rainwater source is that which falls on the yard. Proper placement of plants, trees, and water sources can turn your yard into a water efficient system. Shape the surface of the soil to slow down runoff, raise paths and patios, and sink all planting areas to capture the flow. Choose plants–primarily natives–that can absorb and hold water in their root systems, or pass it down to the water table. This way, rainwater doesn’t run off into the street, where it would be swept away with motor oil, into the sewer system or discharged directly into a local waterway.

The second source of rainwater is the street. Streets aren’t flat; they are graded so that water flows to the curb, down the block to a gutter and into a storm drain. In cities like San Francisco and Portland, storm drains are connected to the sewage treatment plant, and heavy rains cause the sewer plant to overflow raw and partially treated sewer into the bay or river. Other cities connect storm drains to underground creeks, and the polluted water runs straight into the bay or nearby river. By cutting curbs and digging sunken basins into the “right-of way” or “parking strip” area of the sidewalk, you can turn street rainwater from a problem to a resource. Diverted rain that falls on streets can nourish plants, protect creeks, and contribute to cleaner cities.

Store the rain- cisterns and rain barrels
The third source of rainwater is the roof. Even in areas with low rainfall this is an easy way to harvest rainwater.
For example, the roof of a 1,000 square foot house can collect around 600 gallons per ONE inch of rain! In an average year with 12 inches of rain in Los Angeles, that small roof could collect 7,200 gallons.

The rain catchment system
A water catchment system for roof rainwater is simple, and can store water for outdoor irrigation.
200 gallons of storage tucked next to a garage
• Gutters: Roof water gathers in the gutters and runs to a pipe towards the tank.
• “First Flush”: The first rain of the year is the dirtiest as it cleans the roof. This water is directed away from the tank in a “first flush system” and the subsequent water continues to the tank.
• Screen: The rainwater goes through a screen to remove leaves and debris, and then funnels into the top of the covered tank.
• Storage: The tank is dark, to prevent algea from growing, and screened, to prevent mosquitoes from entering.
• Irrigation: A hose attachment is located near the bottom for irrigation.

Rain barrels are a popular way to begin rainwater harvesting, especially in urban areas; they are low cost, and can be installed along houses, under decks, or in other unused spaces.
There is a huge range of options for cisterns, large single storage tanks. They can be made from plastic, ferrocement, metal, or fiberglass, ranging in size from 50 gallons to tens of thousands of gallons.

Indoor use

Ceramic drinking water filter: This highly-effective, passive filter removes pollutants and pathogens including viruses from drinking water.
In Australia, rainwater cisterns supply potable water to thousands of homes. In the US, it’s becoming more common for people to use rainwater indoors for non-potable uses. These systems can reduce or eliminate use of municipal or well water during the rainy season, when outdoor irrigation is unnecessary. Most household rainwater systems use a pump and pressure tank to pressurize water. Many states do not have codes covering indoor rainwater use, and people seeking permits may be required to filter and disinfect the water, increasing system cost and complexity. However, EPA and other research has shown that rainwater harvested using a “first flush” system and protected from light is safe to use for bathing and other household use. Filtering only the small amount of water used for drinking with passive filters such as the ceramic filter shown at left, or with slow sand filters, greatly reduces system cost, and offers an affordable solution for people needing clean drinking water.

Information from shared via Creative Commons Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)

Categories : Case Studies & Application Stories
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