One of the most important factors to consider when planning to purchase or build a home is the adequacy of the water supply. The amount of water available to the home can be equally as important as the quality of the water. The question of how much water is adequate for a private domestic supply is a commonly asked question of the New Hampshire Department of Environmental Services and Water Well Board staff.

Available water supply is a function of both the recovery rate and the storage volume of the well. These two factors contribute to the actual capacity of the supply particularly if the well recovery rate is low. A standard 6 inch diameter drilled well can store 1 ½ gallons of water per foot of well depth. The actual volume of water in storage will depend on the water level in the well and the pump setting depth.

The Water Well Board suggests that a minimum water supply capacity for domestic internal household use should be capable of supplying at least 600 gallons of water within a 2 hour period once each day. This is equivalent to a flow rate of 5 gallons per minute (gpm) for 2 hours. Some homeowners may find this supply of water to be less than desirable depending on the size of the family or if outdoor use is a requirement. Water supply capacities less than this amount may be considered a hardship by many homeowners.

In addition, the New Hampshire Water Well Association and the Water Well Board recommend a flow rate of 4 gpm for a period of 4 hours as an optimum minimum water supply capacity for a private domestic supply. This volume is equivalent to 960 gallons of water delivered within a 4 hour period and should be adequate for all indoor domestic use as well as a modest amount of outdoor use.

Contact your licensed water well contractor or licensed pump installer for information about pumping tests and available options for increasing the capacity of inadequate supplies.

For further information about water supply and wells you may call the Water Supply Engineering Bureau at 271-4087 or 271-1973.