An Introduction to Ground Water Hydrology

Section 3 - More practical aspects of ground water hydrology

Ground Water Demands

The volume of ground water required for households in Maine, that is, the minimum acceptable yield of a water well, depends largely on the lifestyle of the users. Homes with no running water or limited indoor plumbing might get by with a few tens of gallons per day. Well yield of a few pints per hour is sufficient as long as there is adequate storage in the well, which can be achieved in a deep, 6-inch diameter bedrock well, or in a shallow but large diameter dug well.

Homes with one or more bathrooms, dishwasher, clothes washer, cars to wash, and lawns and gardens to water require a well yield of about 5 gpm. Homes that do not utilize water for extensive outside uses, especially watering gardens, can operate on about 2 gpm.

The above well yields assume the average depth of drilled wells to be about 150 feet. A six-inch diameter drilled well can store about 1 1/2 gallons per foot of saturated depth. A 200-ft well with a static water level (the water level when the well is not being pumped) at 25 feet below ground surface stores about 262 gallons of water (175 ft of water x 1 1/2 gal/ft of well = 262 gallons). Two hundred sixty-two gallons of water fulfill the needs of a typical home for about one day (five persons using 55 gallons/day/person). Of course, domestic water use varies from hour to hour and day to day, and one does not wish to run the well dry. Generally, a well is not used at its maximum capacity. It is important also to realize that water needs in homes are greatest during daylight hours. If the well can supply the home during the day and then recover (refill) during the night, the intantaneous yield of the well can be surprisingly low.

Water use per household has increased over the last decades throughout the country, most likely because of the greater use of clothes washers, dishwashers, and indoor plumbing in general. As suggested by Table 2, the volume of water people actually drink has little to do with increases in demand. Table 3 suggests that people with individual water systems (wells) tend to use less water than those on municipal systems, but that by the year 2020, municipal and private users will require about the same quantity of water. It is felt that due to higher treatment, pumping, and distribution costs, and to possible water scarcity, all municipal taps will be metered, and that the water needs of these users will become more conservative.

Introduction Section 1 Section 2 Section 3 Section 4 Section 5 References Links

Last updated on March 25, 2009

Contents

An Introduction to Ground Water Hydrology

Section 3 - More practical aspects of ground water hydrology

Ground Water Demands