Our AquaRain Gravity Fed Water Filter Purifier Systems will provide clean and safe drinking water you can trust, all without having to boil your water, use potentially dangerous chemicals, or rely on man-made energy. Use any water source - lakes, streams, ponds, rivers, springs, cisterns, or even tap water. Here is the best part... our AquaRain Gravity Fed Water Filter Purifier will produce quality drinking water for less than 1¢ per gallon!