Rainwater Harvesting

The harvested water can be used for potable purposes (possibly after testing and treatment). It can be used for people and animals (usually livestock).
Often it is used for watering gardens and food crops.
The surplus water, after usage, can be used for recharging ground water aquifer through artificial recharge techniques. This can also result in improving the quality of the ground water, e.g. less fluoride content in the ground water.

A short list:
Drinking water
Water for the garden and crops
Water for animals
Food preparation and cleanup
Clean water for hygiene purposes

Rainwater harvesting systems reduce dependence on wells and other sources, and, in many contexts, are often a more cost effective source of soft, high quality water.

Harvesting rainwater not only conserves water, it is also saves energy because the energy input required to operate a centralized water system can be bypassed.

Rainwater harvesting is also effective in reducing storm water runoff pollution. When rain falls, it is relatively clean, however it immediately picks up pollutants from the rooftops and pavement. This pollution is carried into storm drains and then into lakes and streams. By collecting storm water from the rooftops and directing it to storage tanks, so it can later be used for irrigation or flushing, decreases the volume and rate of runoff.

The most basic example of a rainwater harvesting system would be of a rooftop collection. The water is collected and transported via ducts, pipes, or gutters. It is then filtered through a mosquito screen into a large barrel. Normally, this water is used to water a garden or for cleaning purposes.



A more complex example would be one used for potable water (drinking water). The water may be collected and diverted using the standard piping, but it is then filtered, often through sand and/or ultraviolet sterilization, and other filters. Along with the filtration process, there are a series of valves to aid in filtering and routing the water through the system. It may then be connected to the plumbing household fixtures for use within the home. Normally, the storage containers involved would be much larger than a simple barrel, as mentioned above.

Rainwater harvesting systems can range in size from a simple plastic tank to a more expensive, contractor-designed and built system.

The simplest method would be to make or purchase a barrel designed to collect water.

It is helpful to estimate annual water supply for home usage. You can use the following formula:

Collection Area (sq. ft) x Rainfall (in/yr.) / 12 (in/ft) = Cubic Feet of Water/Year

Cubic Feet/Year x 7.43 (Gallons/Cubic Foot) = Gallons/Year

For example, a 500 sq. ft roof that gets 36 in/yr. will produce 1,500 Cubic Feet or 11,145 Gallons of water per year.

PLEASE NOTE: This calculation is meant for horizontal areas and does not take into consideration system losses such as evaporation or leakage.

Map of rainfall for your area.

A general rule of thumb is 600 gallons of water per inch of rain per thousand square feet of catchment area. A catchment area is your roof or a special roof built over the water tank for the express purpose of filling up the tank.

If your roof area measures 1000 square feet and you get a 1 inch rain then you could collect 600 gallons of water. Even if you harvest just a portion of that 600 gallons with each rainfall, you could save a good amount of money on your waterbill.

This should be a rediculous question, but the answer is yes. In some places around the world and in the US, it is actually illegal.

You should check with your local government. If it is illegal in your area, please contact your local or regional government to get that turned around.

The Colorado Springs Gazette recently said the following: "The rain barrel is the bong of the Colorado garden. It's legal to sell one. It's legal to own one. It's just not legal to use it for its intended purpose. Meanwhile, when rain does fall, the torrential flood caused by water running off a few thousand acres of roofs, roads and parking lots erodes downstream ranches, undercuts city sewer pipes and really makes Pueblo mad. It's gotten so bad that the city is taxing us all, to pay for $295 million in stormwater projects. So wouldn't it make sense to save a little rain when it falls, keep it from barreling down Fountain Creek, and use it when needed? Of course it would."

However, in some states of the US it may or may not be encouraged, while in certain locals within those states it is actually required to practice rainwater harvesting (Santa Fe County, Bernalillo County and the city of Albuquerque in New Mexico).

Places it is known to be illegal:
Colorado
Utah
Washington State


More information, news, and blog posts:
Thoughts on Privatizing Water
What Privatizing Water means
Rainwater Harvesting Catching on in Some States, Illegal in Others
Grey Water Harvesting
Rainwater harvesting saves water, breaks the law