The cost of a 10,000-gallon tank, PVC lines to and from the house, all filters, UV light, pressure tank, and pump runs about $7,500 to $9,000. To entice more participants—and thereby relieve overburdened water service—Austin, Portland, Oregon, and other cities are offering incentives like tax-free equipment or property-tax rebates to install collection systems.
Good maintenance of a rainwater-collection system is crucial for keeping water quality high, particularly if the water is to be consumed. Gutters must be kept free of leaves, no matter what kind of system you install. If you have a potable-water system, the roof washer has to be drained after a big rain (a simple turn of a valve) and all filters have to be changed periodically.
"I also recommend keeping back overhanging tree branches," says Hari Krishna, president of the American Rainwater Catchment Systems Association (ARCSA). "That way you can keep down the amount of leaves and bird droppings that go into the system."