Water is a valuable resource and yet in the United States we flush much of it down the drain. A rain harvesting system can provide water for your toilets, washing machine and garden, letting you save up to half of the public or well water you currently use.
Rainwater Harvesting is the collection of water that would otherwise have gone into the drainage system, into the ground or been lost to the atmosphere through evaporation. This collected rainwater can be used to flush the toilet, water gardens and even fill the washing machine. Rainwater harvesting systems can be installed in both new and existing buildings, and the resulting water used for all purposes except drinking.
Is it for me? Before making the decision whether or not to go ahead with a system at home or work, it is worth considering your water needs against the cost of installing and maintaining it. While many businesses, housing developments and schools would see financial benefits, most average households find that the cheap and simple installation of a rain barrel or barrels is sufficient to fulfill their needs, if the requirement is for garden watering only.
How does it work? There are a number of different rainwater harvesting systems available. A typical system would collect rain from the roof via a drainpipe into a storage tank (above or underground). A rule of thumb for household water use is to size the tank at 5% of the rainwater supply or of your annual demand, using the smallest of the figures. Check to see how much water your household uses with the water use calculator.
Unless thoroughly filtered, the water is not suitable for drinking, it can be used to supply toilets, outside taps, and the washing machines through a separate pipe network. A control unit monitors the water level in the storage tank and can display this information to the user. If levels drop too low, the system switches to the mains water supply and if it gets too high, an overflow trap allows excess water run into the normal storm drain or out onto the lawn.
Home Systems For rainwater harvesting systems to be practical as the sole household water source, the average annual rainfall must be at least 24 inches. The New England Seacoast receives an average of 44 inches of rain annually. NE has an average of 3-4 inches of rain during the summer months.
If you just want a system to offset your water use, a small system usually can be designed for a few thousand dollars. A state-of-the-art rainwater harvesting system (adequately sized for a typical family and with sophisticated filtering and purification components) for potable water can cost $15,000 to $20,000.
The cost of your system depends on whether you have an appropriate roof surface or have to replace your roof, how big and what kind of cistern you choose, and what level of filtration and purity you require.
For more information check out our the System Components and Household Water Use pages and go to the Texas Guide to Rainwater Harvesting web site. (A comprehensive manual on rainwater harvesting)
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