While not dangerous, an air lock can disrupt water flow throughout a home or building. Understanding what it is, why it happens, and how to fix it can save you a costly service call. An air lock is a pocket of trapped air within a water pipe that prevents the free flow of water. Because air is compressible and water is not, the trapped air acts as a physical barrier. When water pressure from the supply line pushes against the air pocket, the air compresses slightly but does not allow water to pass beyond it.
If you’ve ever turned on a faucet only to hear sputtering, gurgling, or no water at all—despite the valve being fully open—you may have encountered a common but frustrating plumbing problem: an air lock . air lock plumbing