Larrison Residence, Georgetown (Summer 2008)
- Design Team: John and Tommi Larrison, Georgetown, Texas
- System Location: 323 Patricia Road, Georgetown, Texas 78628
- Capacity: 6,500 gallons in two 2,500-gallon tanks and one 1,500-gallon tank
- Catchment Area: 2,625 square foot roof areas
- Water Use: Potable and non-potable use
The Larrisons installed their rainwater harvesting system about 4 years ago to provide for all of their water needs, potable and non-potable. Their goal was to design and build a simple, low-cost, low-maintenance, chemical-free system using their own skills and labor.
The Larrisons have two almost-separate rainwater harvesting systems at their residence; one for collecting and delivering potable water and the other for non-potable water. Rainwater for potable use is collected from the galvanized roof of a 1,725 square foot barn which also houses the storage tanks and the purification system. A galvanized screen filters water collected from the barn roof for debris and relatively large objects before the water flows into two 2,500-gallon storage tanks. The Larrisons use a bottom-feed approach in the tanks because it performs a skimming action in the event of an overflow. From the tanks, the water flows through a check valve into a sediment pre-filter and thence into a pump which feeds a pressure tank. From here it is pumped through a 5-micron particle filter and an ultraviolet filter before being delivered to the house for use.
The non-potable system is much smaller and simpler than the potable system. Water for this system is collected from a portion of the roof on the residence and delivered without filtration to a 1,500-gallon tank placed inside a small metal shed located close to the residence. This water is used to irrigate a small vegetable garden.
There is limited connectivity between the potable and non-potable systems: water is allowed to flow from the potable system into the non-potable system but not vice versa.
The system was designed and installed at a total cost of approximately $5,000. The annual maintenance cost is approximately $100, mainly for filters.
The Larrisons share their experience with others interested in rainwater harvesting and were featured on KXAN's evening news report in July 2006 in connection with a series the TV station was running on water problems in central Texas.
Photograph courtesy of John Larrison