The well water on the property we recently bought was undrinkable (too much iron). Without good prospects for a new well (installers could not guarantee the water quality), we decided to install a rainwater-collection system for our potable water supply.
We installed gutters along the entire house and tied them all to a 6-inch plastic pipe. We fitted the gutters with microscreen filters. From the gutters, the water goes to a first-flush diverter and then on to the 1,100-gallon catch tank. The tank acts as a settling tank between rains. From that tank, we pipe the water to our utility room, where three more 1,000-gallon tanks are tied together. We pull water from them with a pump that sends the water through three 0.5-micron filters and then through two 0.2-micron filters. Then the water passes through a UV sterilizer and over to our 1,100-gallon treated-water storage tank. We pull from this fresh-water tank with another pump to supply pressurized water to the house.
Every three weeks, I refill the freshwater tank and treat it with chlorine. We have been harvesting rainwater using this system for a year, and we love it.
Lumberton, North Carolina