This method of construction can only be used in soft ground. To provide an adequate household supply of water, a well should be able to supply about 5 gallons of water per minute. The availability of water in the surrounding soil or rock determines the water supply rate. Where shallow ground water is plentiful and of good quality, a shallow well may be adequate. To prevent contamination, state regulations require that the space around the casing be sealed in all wells.
Ground water is never completely pure.
Minerals, chemicals, or microorganisms such as bacteria and viruses can easily move with the water as it moves down through the soil. Gasoline, diesel fuel, or other chemicals from leaking underground storage tanks may seep through the soil and into ground water. The type and amount of these materials may vary, depending on the type of soil and rock and the distance these materials travel. Any chemicals or cleaners that are poured down household sinks. Leaking underground storage tanks.