Multi-turn stop valves are very common in the home for shutting off the hot and cold water supply to the faucets or toilet. The problem is the sink or toilet water shutoff valve can leak after turning the handle (usually after turning off the water to replace the toilet tank fill valve) because the internal rubber bonnet packing washer becomes less flexible with age and fails to completely seal against the valve stem. A slow leak may develop around the valve stem – usually a drop or two per minute – which adds up over time causing water damage to the floor, baseboard and wall.

How to Fix a Leaky Toilet Water Shutoff Valve

This is a “straight” style stop valve with 1/2 inch and 3/8 inch compression fittings for a toilet water supply. Straight means the inlet and outlet are on opposite ends. The valve is a multi-turn model because the handle is turned several times to open and close the valve.

Brasscraft Multi-Turn Stop Valve for Toilet Water Supply

Brasscraft Multi-Turn Stop Valve for Toilet Water Supply

The same straight style multi-turn stop valves are also found on hot and cold water to the faucet for this bathroom sink as illustrated below. The valve has compression fittings to make the connection to the 1/2 inch copper water pipe and 3/8 inch faucet hoses.

Sink Faucet Water Supply Shutoff Valves

Sink Faucet Water Supply Shutoff Valves

The following is a right angle stop valve (a.k.a. shutoff valve) for a toilet water supply:

Right Angle Multi-Turn Water Stop Valve

Right Angle Multi-Turn Water Stop Valve

Leaking Water Shutoff Valve Fix

The simplest fix for a leaky toilet water shutoff valve is to tighten the packing nut a 1/4 turn with a wrench. Do not remove the valve, just tighten the packing nut. Hopefully this will be sufficient to compress the rubber packing washer so it seals against the valve stem to stop the water leak.

Water Stop Valve - May Leak at Valve Stem

Water Stop Valve – May Leak at Valve Stem

Did that work? If yes – then check again the next day to verify it’s a permanent fix and you’re done!

Stop Valve Repair Kit

If your sink or toilet stop valve still leaks after tightening the packing nut, inex)pensive rebuild kits are available to replace the worn out bonnet packing washer. Home Depot carries the Brasscraft Multi Turn Valve Stem Repair Kit (Model #: BCSR01, Store SKU #: 1000037226) for about $3. You can also try Ace Hardware for similar stop valve repair kits.

Before explaining how to install the repair kit, let’s examine how the multi-turn stop valve is assembled. The packing nut holds the bonnet packing washer in place and compresses it to make a water tight seal against the valve stem. Stop valves may go for years without being operated. When the handle is turned, the aging bonnet packing washer doesn’t flex as well as it should and minerals in the water may have built up that interfere with the seal against the valve stem.

Water Stop Valve Leak Fix: Bonnet Packing Washer and Packing Nut

Water Stop Valve Leak Fix: Bonnet Packing Washer and Packing Nut

Here’s the fully disassembled stop valve showing the bib washer, threaded valve stem (unscrew it to remove it from the stop body), thrust washer, bonnet packing washer and packing nut:

Water Shutoff Valve Leak Repair: Disassembled Parts

Water Shutoff Valve Leak Repair: Disassembled Parts

A stop valve repair kit will provide a new bib washer, thrust washer and most importantly a new bonnet packing washer. The bonnet packing washer is the component at fault when the stop valve leaks between the packing nut and valve stem.

Water Stop Valve Rebuild Kit Installation

Shutoff the water supply to the entire house before taking apart the valve to install a new bonnet packing washer. The water can be shutoff at the water meter near the street or a main valve at the service entrance inside the home. Why must you shutoff the water to entire house? Because the packing nut and bonnet packing washer are the only thing preventing high pressure water squirting all over the bathroom if you haven’t first shut off the water to the house before removing the packing nut!

The water stop valve repair kit installation steps are:

  1. Shutoff the water to the entire house.
  2. Open a cold water faucet in a kitchen, bathroom or outdoor water hose bib that are lower in elevation than the stop valve in the bathroom.
    Why? Because this will relieve the residual pressure in the cold water pipes AND drain the water out of the pipes that are higher than your stop valve. You don’t want several gallons of water running backwards from the 2nd floor plumbing and out of the open stop valve you’re repairing all over the bathroom floor.
  3. Flush the toilet and hold the handle down to drain the toilet tank.
    This will minimize the amount of water running down the toilet connector hose to the shutoff valve.
  4. Remove the screw from the stop valve handle, then remove the handle.
  5. Unscrew the packing nut with a wrench.
  6. Unscrew the valve stem with your fingers.
    The packing washer and thrust washer will come off with the valve stem.
  7. Slide the packing washer and thrust washer off the valve stem.
    The brass thrust washer can be reused if in good condition after wiping it clean.
  8. Wipe down the valve stem with a soft cloth to remove any crud or dirt.
  9. Replace the bonnet packing washer and optionally the brass thrust washer and bib washer with new ones.
    The bonnet packing washing is what’s causing the leak around the packing nut and valve stem.
  10. Reassembly is the reverse of disassembly.
  11. Turn on the water to the house at the water meter or main service entrance.
  12. Close the water faucets that were opened after they stop sputtering air.
  13. Open the valve to refill the toilet tank.
  14. Check the stop valve for leaks. Tighten the packing washer a 1/4 turn more if it leaks. Repeat if necessary until the leak stops, but don’t tighten the nut so much that you crush the packing washer.

That’s a lot of work just to replace a bonnet packing washer!

Why not replace the entire stop valve for about the same effort with a better 1/4 turn ball design for less than $8? See How to Replace a Leaky Toilet Water Shutoff Valve for instructions.

Thanks for reading,

Bob Jackson

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