Some sites may not be capable of producing the amount of water normally expected for domestic supply (30 gallons per minute [gpm]). However, with an adequate storage tank, a well producing as little as one gpm can be sufficient for domestic needs. In many wells, several hundreds of gallons of water are already stored in the well column. Every foot below water level of a 6-inch diameter well contains 1.5 gallons of water. Here’s the math: There are 1,440 minutes in every day. If a well produces 1 gpm, 1,440 gallons can be pumped in a storage tank daily. Assuming that each member of a family of 4 uses 75 gallons per day, that’s a total of 300 gallons. Total consumption for the entire family is less than 21 percent of the stored water. The well would be required to produce water for a total of only 5 hours a day in order to replenish the tank.
Generally, 5 gallons per minute for 2 hours is considered the minimum acceptable yield in any 24 hour period.