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How To Service a Water Pressure Tank

According to some experts, there are over 15 million private water wells in the United States. Almost all private water wells are equipped with water pressure tanks. These tanks serve the primary purpose of assisting the water pump in supplying water to a residence. They help to prolong the life of the pump by supplying water under pressure without the pump turning on. They accomplish this by virtue of a captive air charge in the tank. That is why they are also known as captive air tanks.

Two different types

  1. Water pressure or captive air tanks come in two different basic configurations.
  2. The old style tank is just an empty galvanized tank that is equipped with an air volume control that keeps the tank charged with air.
  3. The more modern style has a rubber bladder or diaphragm inside that separates the air chamber from the water chamber.

Servicing the tank

  1. If your old style tank becomes water logged, the pump will run frequently or not turn off at all. There are two ways to fix this.
  2. You can shut off the pump and drain the tank, then turn the pump back on and restore the service.
  3. You can replace the air volume control. Air volume controls fail frequently and are not really very effective at doing their job. Many times the serviceman may just remove the control and plug the opening and instruct the homeowner to drain the tank periodically.
  4. Of course, the most efficient fix is to just replace the old style tank with a new captive air tank.

Annual maintenance

  1. At least once a year, check the air pressure in your captive air tank.
  2. Remove the small cap over the air valve. It may be on the side or on the top of the tank.
  3. Using a tire air pressure gauge, check the air pressure. It should read 2 psi less than the cut-in pressure of your pump. You can find this pressure rating by looking inside the lid of the pressure switch, a small gray or black box on top of your pump or installed in the piping to your pressure tank.
  4. If the pressure is low, check the bladder for leaks.
  5. Check the bladder for leaks by depressurizing the water system. Open a faucet somewhere until the water stops running. Air up the captive air tank to the proper level and let it sit for at least 15 minutes. At the end of that time, simply take another reading of the air pressure. If the pressure has dropped at all with the system completely depressurized, the bladder or diaphragm is leaking and the tank needs to be replaced.
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