Air in Water Lines on a Well System

Likely causes

1. 1

   Cause 1: A suction leak on a jet pump

   A jet pump pulls water up the suction pipe by vacuum. Any leak on that side, in a fitting, a cracked pipe or a worn foot valve, pulls air in instead of leaking water out. WAYNE lists a suction piping leak as a cause of a pump that runs but delivers little or no water. That's why you can't find a drip: the leak sucks air in.

   WAYNE also says flexible pipe isn't allowed on the suction line, and the suction piping should slope up toward the pump. A sag or high spot traps air that burps out at the taps.

2. 2

   Cause 2: The water level is dropping to the pump

   When the well can't keep up, the water drops toward the pump intake and the pump starts pulling air with the water. WAYNE lists the water level dropping below the intake as a cause of poor delivery, with lowering the suction pipe as the fix. On a submersible, Goulds lists a pump that's not fully submerged and says to check the well's recovery and lower the pump if possible.

   The giveaway is timing. Air shows up after long showers, laundry or watering, and goes away after the well rests. That's a well that's running low, not a broken pump. See well yield and recovery rate.

3. 3

   Cause 3: A check valve or foot valve that leaks back

   The check valve holds the water column in the pipe when the pump shuts off. Boshart says check valves stop water from reversing and draining back down the well when the pump stops. When one leaks, the pipe drains a little between cycles and the pump pushes the air out ahead of the water next time it starts. You get a cough of air at the first tap you open in the morning.

   WAYNE lists a foot or check valve stuck open as a cause of a jet pump that starts and stops too often. On a jet pump, a leaking foot valve also makes the pump lose prime. Our foot valve and check valve problems page covers replacing them.

4. 4

   Cause 4: Gas in the well

   Some wells carry dissolved gas that comes out as bubbles. Goulds says that if starting and stopping the pump doesn't clear an air-bound pump, the well probably has excessive air or gases. WAYNE's fix for a gassy well on a jet pump is a baffle on the intake. Gas in a well can include methane, which needs venting at the wellhead, so get a water test and a well contractor involved rather than guessing.

5. 5

   Cause 5: The tank's air control on an older system

   Modern bladder tanks keep air and water apart, so a bad bladder usually causes short cycling and pulsing pressure rather than air at the faucet. Boshart lists rapid clicking, short cycling, a fluttering gauge and surging pressure as the signs of a waterlogged tank.

   Older conventional tanks are different: the air sits right on the water, and an air volume control keeps it in balance. WAYNE lists a ruptured air volume control diaphragm and kinked or clogged control tubing among jet pump faults. If you have a plain steel tank with no bladder, that control is a real suspect.

Checks you can do safely

• Note when it happens. First tap in the morning points at a check valve. After heavy use points at a low well. All the time points at a suction leak or gas.
• Watch the gauge with every tap closed. If pressure falls slowly with nothing running, water is leaking back down the well or out somewhere in the house.
• Look at the jet pump's suction side. Check fittings for crusty mineral marks or dampness, and listen for hissing while the pump runs.
• Check the tank. Knock on the upper half. Boshart says it should sound hollow because the tank is mostly air.
• Run a glass of water and watch it. Milky water that clears from the bottom up is fine air bubbles. If it keeps happening, treat it like the causes above.

Fixes

Repriming a jet pump after you fix a suction leak is straightforward. Our how to prime a well pump page walks through it.

How much air goes in the pressure tank?

This is the "air in the pressure tank" people search for, and it's not the same as air in the lines. A bladder tank needs an air charge, set with the tank empty of water, a little below the pressure switch's cut-in.

Boshart's guidance is 10% to 20% below cut-in, with about 15% as a target. It also says at least 2 psi below cut-in for a 20/40 switch and about 6 psi below for a 40/60 switch. So a 40/60 system takes about 34 psi of air.

How to put air in a well pressure tank

1. Turn off the pump breaker.
2. Shut the main valve to the house and drain the tank through its drain valve until the gauge reads zero.
3. Take the cap off the air valve on top of the tank and read it with a tire gauge.
4. Add air with a compressor or bike pump, or let some out, until you reach the target.
5. Close the faucet, turn the power back on and let the pump refill the tank.

The full method is on our pressure tank air pressure page. If the tank won't hold air for more than a few days, the bladder has failed and the tank needs replacing.

When to call a pro

Call a well contractor if the air comes back after you've fixed the obvious leaks, the pump sputters and loses prime repeatedly, you suspect gas in the well, or a submersible's check valve needs replacing down the hole. HomeAdvisor puts a foot valve replacement at $150 to $300 installed, and the average well pump repair at $974. If the well is running low, a contractor can measure the water level and tell you whether lowering the pump is an option.

HomeGuide lists sputtering faucets from air in the lines as one of the signs of a failing well pump. Our page on the signs your well pump is going bad covers the rest.