Why Catch Rain

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What is Rainwater Harvesting?

Rainwater Harvesting Systems (RHS) can be found in all the great civilizations throughout history.

In industrialized countries, rainwater harvesting systems have been developed for the purpose of reducing water bills, watering crops, or providing drinking water by using filtration and catchment tanks to benefit households or entire villages.

Harvesting rainwater is growing in usage once more due to diminishing resources and an ever growing population.


The Uses:

The harvested water can be used for many purposes.
Often it is used for watering gardens and food crops, Gray water usage for toilets, Watering livestock, After purification treatment it could be used as potable water.
The potential list goes on and on.

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


The Benefits:

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 Systems:

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

How it works:

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.


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.

Here in Las Vegas, New Mexico we average more than 17 inches of rain per year.
Las Vegas, New Mexico weather statistics

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

Below is a sample of a catchment system layout.  This does not represent the system that may be installed in your home.