What Is an Air Lock in Plumbing?

Air lock happens when pockets of air keep the water in your pipes from moving through like normal. Air lock in your house's plumbing will leave a water line nearly or completely useless until you fix the situation, causing low water pressure or completely stopping water from reaching your faucets. You may be able to correct the air lock problem with a simple hose and some ingenuity, but the problem may ultimately require the expertise and training of a trained plumber.

Stainless steel sink with mixer tap
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Air lock happens when pockets of air keep the water in your pipes from moving through like normal.

Symptoms of Air Lock

When your house's plumbing develops an airlock in a shower or other plumbing, you'll notice certain problems with how the water flows out of the pipes. The water will sputter out of your pipes, even if you have opened the faucet all the way.

In some cases, the water won't flow out at all, even though other plumbing fixtures work just fine and the shutoffs on the plumbing device are opened. These problems occur mostly in hot water spouts. In mixed faucets, you'll notice that the cold water flows well while the hot water doesn't flow or flows sporadically.

Causes of an Air Lock

Air lock occurs in plumbing systems when pockets of air in a pipe trap the water in the pipe, not allowing the water to flow freely through the pipe. This problem usually occurs in hot water pipes, since the water pressure from the hot water tank won't force the air blockage out of the way. Cold water pipes often connect to the water main, making the development of an air lock in cold water pipes less likely.

How to Fix It

While the air lock problem may seem to some like a reason to call a plumber, you'll save yourself the expense and time waiting for the plumber if you use a homemade airlock fix. You'll need a small section of hose to connect the hot water spout with air lock to a cold water spout.

Secure the hose's connection to the openings on both spouts using clips or hose clamps. Turn on the hot water first, and then turn on the cold water. After about 30 seconds have passed, turn off the cold water first and then turn off the hot water. Disconnect the hose from the hot water spout and turn the hot water on. If the air lock persists, repeat the procedure up to three times.

Mixer Faucet Considerations

For faucets that have both hot and cold water running out of the same spout, you'll need to use a longer hose. Attach the one end of the hose to the spout opening on the faucet that has the air lock problem. Attach the other end to your kitchen sink's spout or the cold water spout for your washing machine, since both should have higher water pressure than other faucets in your house.

Run the cold water from the unaffected spout first, and then turn on the hot water for the affected spout. Leave them running for 30 seconds and then shut off the cold water before the hot water. Contact a plumber if you try this method three times with no results.


Steven Symes

Steven Symes has been writing for six years. His articles have appeared on a number of websites, including some regular columns. Symes has been writing professionally since 2005. He currently holds a Bachelor of Arts in English from Brigham Young University and is partway through an Master of Arts in English at Weber State University.