Proper Way to Bleed a Captive Air Water Pump

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Things You'll Need

  • Adjustable wrench

  • Funnel

  • Bucket

Captive air tanks regulate the pressure of water delivered to a house from a well. Water pumped from the well compresses an air-filled rubber bladder inside the tank. When a faucet is opened in the house, the force exerted by the compressed bladder expels water from the tank at a uniform rate and water pressure in the tank declines. When the tank pressure reaches a preset minimum, the pump turns on and refills the tank with water, compressing the bladder again. This sequence maintains steady water pressure into the house while reducing the number of pump on/off cycles. Most shallow wells less than 25 feet deep use captive air systems with surface-mounted "jet" pumps instead of submersible pumps. Any time the system is opened for repair and water in the suction pipe drains out, priming and bleeding the jet pump is necessary to restart.

Step 1

Close the control valve in the line between the pump and the captive air tank.

Step 2

Unscrew the priming plug from the top of the pump casing with an adjustable wrench.

Step 3

Place a funnel into the priming opening. Fill a bucket with water and pour water into the pump casing until the suction line and pump casing are full.

Step 4

Reinstall the priming plug loosely to allow air to bleed from the pump.

Step 5

Turn on the pump and monitor the sound of air bleeding from the priming plug. When air stops bleeding, turn off the pump. Remove the priming plug and pour more water into the pump casing until the suction line and pump casing are full again. Reinstall the priming plug loosely and restart the pump.

Step 6

Repeat the process until water flows steadily out of the priming plug and there is no sound of air escaping. Depending on the length of the suction line and the depth of the well, several repetitions and as long as 15 minutes may be required to fully prime/bleed the pump.

Step 7

Reinstall the priming plug and tighten securely after all air is bled from the pump. Open the control valve between the pump and the captive air tank.

references & resources

Gus Stephens

Gus Stephens has written about aviation, automotive and home technology for 15 years. His articles have appeared in major print outlets such as "Popular Mechanics" and "Invention & Technology." Along the way, Gus earned a Bachelor of Arts in communications. If it flies, drives or just sits on your desk and blinks, he's probably fixed it.