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How to Fix a Leaking Shutoff Valve

This quick DIY fix for a leaky water shutoff valve is something even a novice can handle. Follow our how-to steps and photos for complete instructions.

By the DIY experts of The Family Handyman Magazine

Fix a leaking shutoff valve

The plumbing supply shutoff valves behind toilets or under sinks can go for years without being turned off and then reopened again. That inactivity can cause the neoprene washers to become either brittle or crusted up with mineral deposits, and they lose their ability to seal leaks.

Occasionally, after shutting off a toilet supply valve to replace the tank plumbing parts, you may find that the shutoff valve leaks through the packing nut once the valve is opened again. To remedy this, most plumbing pros advise first using a groove joint pliers to tighten the packing nut one-eighth turn clockwise (Photo 1). If the neoprene washers are still flexible and clean, this should work to stop the leak.

If the leak persists, before replacing the entire valve, try this. Turn off the water at the house's main shutoff, then disassemble the problematic shutoff valve without disconnecting the valve from either the water supply line or the line leading to the toilet. Unscrew the handle, the packing nut and the threaded valve stem (Photo 2).

Clean the washers with a cloth and flex the neoprene to try to get it supple again. Avoid gumming up the inside of the shutoff valve; don't use any pipe dope or plastic tape on the valve stem's threads. Reassemble the shutoff valve, turn the main house valve back on and check for leaks. If the valve leak persists, turn off the main water shutoff valve, then disconnect the valve and replace it.

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Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

    • 4-in-1 screwdriver
    • Slip joint pliers

Comments from DIY Community Members

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1 - 8 of 8 comments
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May 01, 8:04 PM [GMT -5]

Excellent advice, saved me the hassle, especially since i just replace the floor in the bathroom, got the toilet all set up in its kinda tight space. I didn't want to have to fight behind the toilet and walls.

February 06, 4:01 PM [GMT -5]

I had a new washer and dryer installed today and the cold water valve was leaking. After fumbling thru different sites, I found the solution with the Handyman........It was an easy fix, with simple to follow instructions.......This site is invaluable to the once middleclass household.........I can't afford to pay someone to fix things, so your site is greatly appreciated.....Thank you!!

November 18, 10:20 AM [GMT -5]

Thanks for this tip. this worked for me!

October 23, 12:00 PM [GMT -5]

Great advice about the 1/8 turn fix. Worked perfectly. The photos were very helpful. You saved me from embarking on (for me) a big project of disassembling the valve or possibly replacing it.

A word of caution: Don't go a bit past the 1/8 turn, even if the nut seems willing - it'll make it more difficult to turn the valve handle, and these valves and handles are not what one could call heavy-duty. If I were to do this again, I'd start out with maybe 1/16 of a turn and see if that does the trick.

September 06, 5:15 PM [GMT -5]

Well, that was easy, thanks to your advice!

December 31, 7:05 PM [GMT -5]

The 1/8 turn worked like a charm. Covering the plier teeth with masking tape was a simple and ingenious idea.

September 16, 9:30 AM [GMT -5]

If it keeps leaking just replace it an new one only costs 6 bucks, not worth the touble of taking it apart and messing with it.

September 07, 12:59 AM [GMT -5]

Seems so obvious, but this article was totally on the money for me.

I thought I'd have to replace the leaking valve after having to turn it off to replace the kitchen faucet. All it needed was a 1/8th turn, just as prescribed.

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