At 39,000 gallons, our system is large enough to store seven months of water.
Because we drink the water, our storage tanks are coated on the inside with an FDA-approved food-grade resin and on the outside with gelcoat, an opaque resin that blocks out sunlight and helps prevent algae buildup. Before the water enters the house, a 5- and then a 3-micron carbon filter take out any suspended sediment that the roof washer (which filters most debris) missed. Then the water passes a UV light that kills bacteria. We clean filters from the roof washer at a self-service car wash. We change the 5-micron filter every month and the 3-micron filter every three months; the UV light is cleaned every five months and replaced every 14 months.
We stretch our supply by using water-saving toilets that require only 1.2 gallons per flush, a front-loading washer that uses 50 percent less water, and by limiting showers to two minutes, which is not popular with our guests. At just under $25,000, the cost to install our system wasn't cheap compared with using city water or drilling a well. But now that it's running, we pay only for the electricity to run a 1-horsepower pump and $150 a year to replace all the filters. The payoff is delicious: chemical- and mineral-free tap water that's far better than anything from city or well sources. Dishes, clothes, and skin rinse clean, and there's no buildup of iron or lime on the fixtures. Plus, we have a modicum of self-sufficiency, which is worth a lot to us these days.