Rain Water Harvesting

The drought in Texas continues to be devastating across the state.  Forecasters today are suggesting that the drought could continue for the next seven years.  Because of the drought we have experienced recently the interest in rainwater harvesting has increased.  Captured rainwater presents a low cost, high quality, readily available source of water for landscape and greenhouse use. 

            The purity of rainwater as an irrigation source has proven benefit.  Proper rainwater system design includes a “roof washer”, allowing the first portion of rainwater from an event to be captured before entering the tank.  This reduces the impurities captured by the holding tank.  A filter is also recommended prior going into the tank.  Filters further reduce impurities from entering the system, and more importantly decreases small particles which can plug irrigation nozzles on the output side.

            Harvest potential can be calculated based on roof square footage to determine tank size.  A roof drip-line footprint will provide .6 gallons per square foot per one inch of rain.  Measuring the square footage underneath the roof drip-life multiplied by .6 gallons/ foot will equal total gallons per one inch of rainfall.  Matching monthly rainfall with projected utilization should provide a basis for tank sizing.  A wide variety of tank sizes and designs are available.  Attractively designed tanks are available in various shapes and sizes can be purchased to enhance the appearance of a rain collection system.

            Looking into the future, demand for water presents real concern for Texas citizens.  The municipal use will double by year 2060.  Manufacturing will logically follow suit with a projected increase.  There is a projected decrease in irrigation.  Given there is no new water, and ground water in many areas of the state are already stretched or short, better utilize the captured rainwater can reduce individual homeowner demands and thus state-wide needs.