How to Fix a Leaking Shutoff Valve

Fix a leaking shutoff valve and save yourself the cost of a visit from the plumber.

Next Project

An hour or less




Less than $20


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.

Tools Required

  • 4-in-1 screwdriver
  • Slip joint pliers

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. Fixing the valve is usually pretty simple if you know what to do.

Project step-by-step (2)

Step 1

Tighten the Packing Nut

  • Tighten the packing nut on the toilet shutoff valve one-eighth turn clockwise to try to seal a leak around the nut.
    • Pro tip: Wrap cloth or masking tape on the plier’s jaws to protect the nut’s finish. Use light, steady pressure so you don’t damage the water lines.

Step 2

Disassemble the Shutoff Valve

  • Disassemble the shutoff valve—leaving the toilet and supply lines intact.
  • Clean the washers with a cloth.
  • Flex the neoprene to try to get it supple again.
    • Pro tip: Avoid gumming up the inside of the shutoff valve; don’t use any pipe dope or plastic tape on the valve stem’s threads.
  • Turn off the house water main before taking apart the toilet shutoff valve.
    • Note: Properly sized replacement washers for the shutoff valve are available from plumbing supply houses and better hardware stores that stock a large inventory of repair parts.
  • If this step doesn’t stop the leak, you’ll need to replace the whole valve.