We are looking at buying a piece of property - 23 acres in western Montana. The sole source of water for the house is an underground spring fed concrete cistern. (Two wells have been drilled on the property, both in the 400' range, one collapsed and one went dry.) The cistern is near a surface creek, but appears to get its water through an undergound spring. It's approximately 8' in diameter, 12' deep, and has a series of 2" holes in the lower 6', where we assume it is getting water from an underground spring. The only cisterns I have been able to find any information on are rain fed, or spring fed ones for livestock or gardens. Does anyone know anything about inspecting, using, maintaining, filtering, etc underground spring fed cisterns for human consumption and household needs? Any info would be appreciated.