How to Fix a Gate Valve That Doesn't Close

Gate valves are often used for main supply valves in houses. Since they don't depend on washers to stop the flow of water, they are useful in spots where a washer might harden, decay or become dislodged over a long period of disuse. That is not to say gate valves can't develop problems of their own over time when neglected.

Common Cause

The side and bottom guides that permit the gate portion of the valve to close and shut off water flow are ideal capture points for small bits of debris. These have a tendency to build up when the valve is left, as most supply valves are, continually open. In most instances, getting the valve to fully close is a simple task.

Simple Solution

The cleanest, simplest approach to getting a stubborn gate to close is to flush it out. Start by closing the gate valve as far as possible without applying excessive pressure. Then, open a faucet inside the house to provide an effluent outlet. Since the goal of this exercise is to flush debris out of the plumbing system, a bathtub or outside hose bib is the best choice. Most other household faucets are equipped with aerator screens that will capture and may become clogged with debris. Open the gate valve as far as possible. Close the gate valve. Again, don't apply too much pressure when closing the valve to avoid damaging its inner workings. Repeat the cycle of opening and closing the valve until the gate seats fully or the gate stops making any progress toward closing. The action of moving the gate inside the valve channel, combined with the resulting water turbulence, usually breaks loose and flushes any built-up debris out of the valve. If the valve stops making downward progress without shutting off the water flow, try taking the valve apart for cleaning.

Clean the Valve

First, shut the water off at the curb or meter. Never remove a valve or faucet that is under pressure. Then, open the gate valve fully. Remove the top of the valve housing by attaching a wrench to the top of the housing. Do not loosen the nut on the valve stem. This is the packing nut that holds the packing that prevents water from leaking around the handle. Loosen and remove the top of the valve housing. The valve stem and gate will remain attached to the housing. Inspect the outer edges of the gate for irregularities and scrape off any mineral deposits before reassembling the valve. Use a small screwdriver to scrape any loose debris out of the grooved channel that acts as the valve's gate guide. Clean this thoroughly; even a small amount of buildup will prevent the valve from closing completely. Slide the gate back into its guide and tighten the top of the housing with a wrench. Turn the water supply on and test the valve again. The valve may need to be replaced if severe pitting or corrosion are present inside the guide channel or gate.


Reduce the likelihood of continued problems with your gate valve with some simple preventive maintenance. Simply close the valve fully and reopen it about every six months to keep the guide path clear. If you have extremely hard water or old, iron pipes that produce large amounts of rust, it may be a good idea to open and close the valve about every three months.