Collecting rainwater from roofs and storing it for future use is a practical way to maximize the benefits of precipitation in South Central Texas. In fact, cisterns that captured rainwater were a common way for early settlers to store water for everyday use. This old practice has now become modernized in Central Texas as several builders are installing rainwater harvesting systems to supply most or all of the water demands for homes and businesses.
One famous example is the Lady Bird Johnson Wildflower Research Center in Austin. Typical rainwater harvesting systems include a large catchments area such as the roof of a home, gutters to transport rainfall, and screens which filter leaves and debris. A roof washer (with a 30 micron filter) is installed just before storage in large tanks (50 to 15,000 gallon fiberglass). The storage tank may be buried underground or hidden among landscape. One estimate by the Texas Cooperative Extension said that 0.6 gallons of water can be harvested for each square foot of roof per inch of rain received, depending on collection efficiency. For example, if an inch of rain falls on a 2,000 square foot roof surface, then 1,200 gallons of water can be harvested. An average rainfall year of 40 inches in Brazos or Robertson counties would result in as much as 48,000 gallons of water harvested from rain. With appropriate conservation measures, this may be sufficient to supply household needs.
Rainwater harvesting can also be done by simply placing barrels or buckets outside prior to a rain event. Harvested water could be used for watering plants, however, this water would not be suitable for human consumption unless it is filtered and kept in a closed container.
To best determine whether rainwater harvesting would be a practical way for your family to supply all or some of your water demands, we recommend calculating a water budget using the online calculator found on the Texas Agrilife Extension Service website. This website includes a detailed description of rainwater harvesting systems.
Also, check out the extensive rainwater harvesting manual developed by the Texas Water Development Board. It includes everything from rainwater harvesting system components, water treatment, design guidelines, water demand calculations, and cost estimates.
$25 Rain Barrel Rebate
Remit the above completed application to:
Brazos Valley Groundwater Conservation District P.O. Box 528 Hearne, Texas 77859