How to Adjust the Air Pressure in a Bladder Tank

Your above-ground well water pump has a blue bladder tank that the pump fills with water to build water pressure inside the home. The tank is usually in the vicinity of the water pump. The bladder tank pressure tells the pressure switch when to turn on and off. Occasionally, you'll need to adjust the bladder's air pressure. The best way to check the bladder tank air pressure is with a digital air pressure gauge. Digital gauges are more accurate than standard stick gauges. Adjusting the bladder tank air pressure requires an empty bladder tank. Most air pressure adjustments take only a few minutes.

Turn off the water pump by either unplugging the power cord from the wall outlet or turning off the circuit breaker. Turn off the circuit breaker to the hot water heater.

Open a cold water faucet that is closest to the bladder tank and allow the bladder tank to empty. Continue running the water until the water stops flowing from the faucet. Turn off the water faucet.

Remove the cap from the air valve stem on top of the bladder tank. Check the air pressure with a digital pressure gauge or a digital tire pressure gauge. The air pressure should be 2 psi below cut-on pressure on your pressure valve. For example, if your cut-on pressure is 30 psi, the bladder tank pressure should be 28 psi.

Decrease the air pressure by depressing the stem in the centre of the valve with the tip of a flathead screwdriver. Release air pressure in small increments and recheck with the air pressure gauge.

Increase the air pressure by adding air into the valve stem with an air compressor or foot pump. The valve stem operates the same way a bike or car tire stem operates. Add the air in small increments and recheck with the pressure gauge.

Twist the valve cap back onto the valve stem. Plug the water pump power cord back into the outlet or turn on the circuit breaker. Turn the circuit breaker back on to the water heater.


You may need to reprime your water pump after making your air adjustments.

Things You'll Need

  • Digital air pressure gauge
  • Flathead screwdriver
  • Air pump
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About the Author

Kenneth Crawford is a freelance writer with more than 10 years of experience. His work has appeared in both print and online publications, including "The American Chronicle." Crawford holds an associate degree in business administration from Commonwealth College.