Air in Well Water Lines? 5 Causes of Sputtering Faucets and How to Fix Them
You turn on a faucet and it coughs, spits and sputters before the water runs smooth. On a private well, air in the water lines is a clue, and it usually points to one of five problems.
Some are harmless and some will burn out a pump if you ignore them. This guide shows you how to tell which one you have, what to check first and when to call a well contractor.
Boreholeflow is reader supported. When you buy through links on this page, I may earn a commission at no extra cost to you. Read the full disclosure.
- Air in only the hot water? The problem is usually the water heater, not the well.
- Sputtering after long use often means the pump is drawing the well down and sucking air.
- Constant spurts plus a pump that clicks on and off point to a leak in the drop pipe or a bad check valve. Get that fixed before it ruins the pump.
Air in Water Lines Checker
5 Causes of Air in Well Water Lines
1. The well water level is dropping to the pump
If the pump pulls water out faster than the well can refill, the water level drops to the pump intake and the pump starts gulping air. You notice it most after long showers, laundry days or garden watering, and during dry spells.
Other signs are sputtering that comes with sand or cloudy water, and a pump that runs a long time. Ease off heavy use for a few hours and see if it clears. Our guide on how to test well flow rate shows you how to check what your well can deliver, and how deep is my well helps you find out where the water sits.
A pump protection device that shuts the pump off when it runs dry can save the motor. See our well pump protection devices guide.
2. A leak in the drop pipe or a bad check valve
A check valve keeps water in the pipe when the pump turns off. If it fails, or if the drop pipe has a hole above the water line, water drains back down the well and air takes its place. The next time you open a tap, that air comes out first.
Look for a pump that turns on even when nobody is using water, pressure that slowly falls on the gauge, or a pump that short cycles. This is a job for a well contractor because the pump has to come out of the well.
3. A failing air volume control or pressure tank
Older galvanized pressure tanks without a bladder use an air volume control (AVC) to keep the right air cushion in the tank. When the AVC fails, the tank can end up with too much air, which then blows out of your faucets.
Modern bladder tanks do not let air into the water at all, but a waterlogged tank causes rapid cycling. See signs of a bad pressure tank and our Flotec air volume control kit review.
4. Dissolved gas in the groundwater
Groundwater can carry dissolved gases like carbon dioxide, hydrogen sulfide and, in some areas, methane. When the water comes up to lower pressure in your home, the gas comes out as tiny bubbles. The water looks milky and clears from the bottom of the glass up.
Hydrogen sulfide smells like rotten eggs, which our rotten egg smell guide covers. Methane has no smell but can build up in an enclosed space and is a fire risk. If your water fizzes, spurts hard or the well cap hisses, have the water tested for methane. Penn State Extension has a clear explainer on methane in water wells.
5. The water heater (hot side only)
If only the hot taps sputter, look at the water heater. Overheating can make water flash to steam, and sediment in the tank can trap gas. Check that the thermostat is not set too high and that the temperature and pressure relief valve is working, then flush the tank.
If you also see milky hot water, it may be harmless air coming out of hot water. That clears in seconds.
Air in the Lines After a Power Outage or Repair
Air in the pipes after a power cut, a pump replacement or plumbing work is normal. When the system drains or is opened, air gets in, and it takes a few minutes of running water to push it out. It should not come back.
How to Get Air Out of Your Water Lines
- Turn the pump on and let the pressure tank fill until the pump shuts off.
- Open the cold tap at the lowest point in the house, such as a basement sink or outdoor spigot.
- Open every other faucet from the lowest floor to the highest, one at a time.
- Let each one run until the water flows steady with no spitting, usually a minute or two.
- Close the faucets in reverse order, highest first, then flush each toilet once.
- Watch the pressure gauge. If air comes back within a day, one of the causes above is still there.
A cheap liquid filled gauge on the tank tee makes this much easier to read than an old dial.
Liquid Filled Pressure Gauge, 0 to 100 PSI, 1/4 inch NPT
A steady, easy to read gauge for your pressure tank tee. Watch it while no water is running: if pressure creeps down, water is leaking back somewhere.
Check price on AmazonWhen to Call a Well Contractor
- Air keeps coming back after you bleed the lines.
- The pump turns on when no water is being used.
- You get sand, mud or cloudy water along with the air.
- The water fizzes hard or the well cap hisses, which can mean methane.
- The pump runs for a long time or will not shut off. See well pump won’t shut off.
If the pump has to come out, our well pump replacement cost guide shows what to expect. Not sure if the pump is the problem? Start with signs your well pump is going bad.
Frequently Asked Questions
Why is there air in my well water lines?
The most common causes are a low water level in the well, a leak in the drop pipe or a failed check valve, a faulty air volume control on an older tank, dissolved gas in the groundwater, and, for hot water only, the water heater.
Is air in well water dangerous?
Air itself is not. But sputtering can be a sign the pump is running dry, which can damage it, and fizzy water can mean methane, which is a fire risk in enclosed spaces. Find the cause.
How do I get air out of my well water lines?
Open the lowest faucet in the house first, then each faucet up to the highest floor, and let each run until the flow is steady. Close them in reverse order.
Can a bad pressure tank cause air in the water lines?
Yes, on older galvanized tanks with an air volume control. Bladder tanks do not let air into the water, but a waterlogged bladder tank causes fast pump cycling.
Why is my well water milky?
Milky water that clears from the bottom of the glass up is tiny gas bubbles. It is usually harmless air, but if it happens all the time, test the water for methane.
