How to Repressurize a Pressure Tank

Private home, well water systems use a pressure tank to regulate the overall water pressure. Inside the pressure tank is a rubber air bladder which maintains the draw-down pressure of the water. Over time, the air pressure inside the bladder may require additional air to maintain the water pump efficiency. Indications of low air pressure inside the bladder may be a constant on and off operation of the water pump along with a hard knocking noise called water hammer.

Things You'll Need

• Pressure gauge
• Compressed air source
• Bicycle hand pump (optional)

Instructions

1. Shut off the electrical power to the water pump system.

2. Drain the water from the pressure tank to relieve all water pressure.

3. Locate and remove the air filling valve on the air bladder. In most cases, the valve is on the top-center of the pressure tank and resembles the same type of air valve that is on a bicycle or automobile tire.

4. Press the pressure gauge to the air bladder filling valve. The air pressure reading must be 2 lbs. per square inch less than the cut-in or pump-on pressure. In most cases, the cut-in pressure is 30 psi, so the air bladder pressure should be 28 psi.

5. Fill the air bladder using a compressed air source or from a bicycle hand pump. Check the pressure often when filling the balder. If too much air has been added, depress the center valve with a fingernail to relieve internal pressure.

6. Replace the air bladder valve cap. Close the drain valve. Turn the electrical power on. Allow the water system to build pressure.

Tips & Warnings

• Older, galvanized water pressure tanks, with no air bladder, use the same process for adding air; however, these tanks are not drained of the water when filling with compressed air. If no compressed air is available, drain the galvanized tank of all water. Allow air to enter the tank by leaving the drain valve open for a minute after all water has exited. Close the valve and turn the power on to the pump system. The air inside the galvanized tank will pressurize the system.

• Never exceed the bladder air pressure capacity as the bladder may rupture.

References

• Inspectapedia: How to Set or Adjust the Air Pressure in Bladder Type Water Storage & Pressure Tanks
• Inspectapedia: How to Add Air to a Water Pressure Tank
• Government of Alberta: Pressure Tanks