Well Pressure Tanks

A pressure tank is the part of a well which actually stores the water. The water stored in the tank is sent up from the well by the pump. The right type of pressure tank can actually extend the life of the pump, by decreasing the amount of times the pump must turn on and off.

When water enters the pressure tank, the air above it is compressed. If a tap is turned on, the water is forced out of the tank by the air pressure in the top of the tank. When the air is almost finished forcing the water out of the pressure tank, the pump will start and bring more water in. Pressure tanks are important because they keep the well's pump from wearing out quickly, since it would have to turn on every time water was being used.

There are a few different types of pressure tanks for wells. The standard pressure tank used to be a 40 gallon (151.4 liters) galvanized tank. This type of tank, although it is 40 gallons, only holds about 7 or 8 gallons (26.5 or 30.2 liters) of usable water, with the pump turning back on after a few gallons of water are used. As this tended to wear the pump's motor out, this type of tank has been replaced for the most part by the bladder tank and diaphragm tank.

Bladder pressure tanks have a bladder inside them, which fills with water. As the bladder fills, air is trapped between the bladder and the wall of the tank, compressing the air until it is the same as the incoming water pressure. When a tap is turned on, the pressure drops, and the air pressure inside the tank forces water out. Diaphragm pressure tanks operate in a similar manner, but the bladder is permanent and not replaceable.

Well pressure tanks come in many different sizes, but the larger the tank is, the less often the pump has to turn on, extending its life. It is generally recommended that the capacity of the tank is at least twice the pumping capacity of the well's pump, but this is sometimes ignored, as larger pressure tanks do cost more money.

When installing a pressure tank, make sure it is not in a location that will allow it to freeze. Pressure tanks should not be buried, but should be installed in basements, utility rooms, or other protected areas. If they are installed outside, they should be protected from freezing, whether by heat lamps or insulation.