Why Is My Main Water Shut-Off Valve Leaking? A Phoenix Plumber Explains.

2016 Sep 07
Posted in: Plumbing

If you’ve noticed that your home’s main water shut-off valve is dripping water, you’re probably wondering if this is a sign of a larger plumbing issue.

Well, it could be that you have a standard gate valve, which is prone to leaking, corrosion and damage.

The long-term answer is to replace it with a ball-valve. These valves last longer and are less likely to leak.

First, though, try the following DIY solutions to stop the leak:

  • Tighten the packing nut with a wrench
  • Add more packing material to packing nut
  • Replace packing washer

We’ll walk you through each of these steps below.

Note: If your valve is still leaking after these steps, you’ll need to have a professional replace your gate valve with a ball valve.

Tighten the packing nut 

The packing nut is responsible for making a watertight seal where the valve stem meets the water line. So, if there is a leak at the valve stem, it most likely means the valve is not shut off all the way. 

The first thing you should do to stop the leak is to tighten the packing nut.

To tighten the packing nut, follow these directions:

  • Use a wrench to give the packing nut a ¼ turn
  • Check for leaks
  • If the leak continues, try turning the packing nut tighter and check again

If the leaking doesn’t stop, move on to the next option...

Add more packing material to the packing nut

What you’ll need:

When tightened, the packing nut on your main water shut-off valve binds down the “packing material” against the washer to seal off water.

Over time, though, this packing material can harden or disintegrate. And when this happens, it won’t form a solid seal and will cause leaking.

When this happens, you’ll need to follow these steps to replace the packing material:

1. Shut off water from street (usually this needs to be done by your utility company or by a professional plumber). 

2. Turn on a faucet in your house to let out all residual water inside your home’s water line.

3. Loosen the shut-off valve handle as far as possible.

4. Loosen the packing nut and remove any old packing (if it’s made of teflon or other fibers, you can pull it out using a toothpick). You may see a rubber gasket instead of teflon packing material, in which case, you’ll want to remove the rubber gasket completely.

5. Wrap new packing 3 times around the stem counterclockwise.

6. Screw the packing nut back on, making sure the packing catches and fits snugly into the packing nut. Be careful not to overtighten the packing nut.

7. Turn the water back on and check for leaking.

Still see the leak? Then let’s move on to the next step...

Replace the washer

What you’ll need:

  • Wrench
  • Replacement packing washer (found at most hardware stores)

If your water valve is still leaking at this point, you may have a bad washer that needs to be replaced. 

To replace your washer, follow these steps:

  • Remove the valve handle 
  • Remove the packing nut with a wrench
  • Remove the old washer and replace with the new one. Note: You will need to make sure the new washer matches in size. We suggest removing it and taking it with you to a hardware store to be sure the replacement is a match.
  • Test for leaking

If your faucet is still leaking at this point, you’ll need to have a professional take a look at your shut-off valve.

The best solution for a leaky gate valve is to replace it with a ball valve.

Need an AZ plumber?

If you’ve attempted all of the above steps but your main water shut-off valve is still leaking, you’ll need to upgrade to a long-lasting ball valve.

If you live in the Phoenix area, schedule your appointment with George Brazil today.

We’ll send over a certified plumber who can replace your leaky valve in no time.

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