What is 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
Harvesting rainwater is growing in usage once more due to diminishing resources
and an ever growing population.
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
The potential list goes on and
A short list:
Water for the garden and crops
Water for animals
Food preparation and cleanup
Clean water for hygiene purposes
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
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.
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
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.
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.