There are two primary types of private wells – bored and drilled. Bored wells are shallow, usually less than 100 feet deep. They consist of a large, cement cylinder casing with a concrete cap. The well casing can be 2 – 3 feet in diameter. A submersible water pump is placed in the well casing. In contrast, a drilled well is a deep well and has a narrow shaft. A well house or other structure usually protects the wellhead. In both wells, water lines run underground to the house.
The water lines connect to a reservoir called the bladder or pressure tank. It contains a large air-filled bladder. When the water pump turns on, it pumps water into the bladder tank. The water compresses the bladder. A pressure switch turns the pump off when the pressure reaches a certain level. When a faucet is opened, pressure in the bladder tank forces water into the house. When the pressure in the bladder tank falls, the well pump turns on to increase the pressure. This keeps the well pump from running continuously and burning out.