Understanding Water Wells and How They Work
A well is the most common way to obtain groundwater for household use. A well is basically a hole in the ground, held open by a pipe (or casing) that extends to an aquifer. A pump draws water from the aquifer for distribution through the plumbing system. The depth to which wells are constructed is determined by factors such as 1) depth to groundwater, 2) the groundwater quality, and 3) the geologic conditions at the well site.
Pumping Systems
A water system is needed to pump the water out of the well to the surface and deliver it under pressure to the place where you will be using it. A typical home water system consists of a pump, a pitless adapter or unit, and a pressure storage tank and control devices that allow the system to operate automatically.
Pumps
A pump is used to push or lift water from the well into your household plumbing. The correct size of pump and pump motor depends on the well diameter, the water level in the well, the number of plumbing fixtures, the amount of water use, and the peak water demand. Peak demand usually occurs during the morning and evening hours. Pumps are rated in gallons per minute (gpm) and pump motors are rated in horsepower (hp). A typical pump for domestic use might have a 10 gpm pump with a ½ hp motor. Special water needs — such as for irrigation, heat pumps, or livestock — can increase peak demand and require a larger pump.
A submersible pump, which is the type most often used in drilled wells, consists of a pump and motor unit, typically 3½ inches in diameter and 2 to 3 feet long. The pump is placed directly into a 4″ or larger well, below the water level.
Pressure Tanks
As the name implies, a pressure tank contains water under pressure. As water is pumped into the tank, it compresses the air in the tank until the pressure reaches a preset level — typically from 40 to 60 pounds per square inch (psi) — which automatically shuts off the pump. When a faucet is opened, the air pressure in the tank forces water through the pipes until the pressure drops to another preset level — usually from 20 to 40 psi — which starts the pump again. A pressure switch starts and stops the pump at the preset pressure levels, and allows the system to work automatically.
