What is an air lock in plumbing?

Air lock in your house's plumbing will leave a water line nearly or completely useless until you fix the situation. 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.


When your house's plumbing develops an air lock, you will 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 will not 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, or in mixed faucets you will notice that the cold water flows well while the hot water does not flow or flows sporadically.


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 will not 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.


While the air lock problem may seem to some like a reason to call a plumber, you will save yourself the time waiting for the plumber and the expense of paying him if you take care of the air lock in your house's plumbing yourself. You will 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 Faucets

For faucets that have both hot and cold water running out of the same spout, you will 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, and the 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 effected 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.