The Larrisons installed their 6,500-gallon rainwater harvesting system in two 2,500-gallon tanks and one 1,500-gallon tank using 2,625 square foot roof areas.
The purpose of the system is to provide for all water needs, both potable and non-potable using a simple, low-cost, low-maintenance, chemical-free system.
The rainwater for potable use is collected from the galvanized roof of a 1,725 square foot barn that 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 the two 2,500-gallon storage tanks. A bottom-feed approach is used to skim in the event of overflow. From the tanks, the water flows through a check valve into a sediment pre-filter into a pump that 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. 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.