How to Fix a Leaking Main Water Shut-off Valve 

If you have an old style gate or globe valve , they are prone to leaking, corrosion and damage , which is an easy way to figure out if that’s what’s causing the leaking.

We recommend replacing the gate valve with a ball valve, which lasts longer and is less likely to leak.

Before replacing the valve, try these two things first to try and stop the leak:

• Tighten the packing nut with a wrench
• Replace valve stem packing material or washer
• We’ll walk you through each of these steps below.

Tighten the packing nut

The packing nut makes a watertight seal where the valve stem meets the water line. So, if there is a leak at the valve stem, it probably means the valve is not turned all the way off.

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

To tighten the packing nut:

• Turn the packing nut ¼ turn using a wrench
• Check for leaks
• If the valve is still dripping, try turning the packing nut tighter and check again

If the leaking hasn’t stopped, there’s another option.

Replace the packing material under the packing nut

Tools you’ll need:

• A wrench
• Replacement packing material (can be found at most hardware stores)
• When you tighten the packing nut on your main water shut-off valve, it binds down the packing material against the washer to stop any water from getting through. Over time, though, this packing material can form a solid seal because it hardens or disintegrates, which causes the valve to leak. When this happens, you’ll have to replace the packing material by following these steps:
• Shut off the water from the street at your meter box (turn the valve next to the meter counterclockwise)
• Turn on a faucet in your house to let out all the water that’s inside your water line
• Remove the shut-off valve handle
• Remove the packing nut and any old packing (if it’s made of Teflon™or other fibers, a toothpick can be used to pull it out).
• If you see a rubber gasket instead of Teflon™, you’ll have to remove the rubber gasket completely. Since you’ll need to make sure the new washer is the same size as the old one, your best bet is to remove the washer and take it with you to a hardware store so you buy the correct size.
• Wrap the new packing around the stem 3 times counterclockwise or just replace the rubber washer
• Screw the packing nut back on, making sure the packing fits tightly into the packing nut. Be careful not to overtighten the packing nut
• Turn the water back on and check for any leaks

If your shut-off valve is severely corroded or the repair uncovers pipe damage, JB Water & Air can step in. Our Mesa leak detection and pipe repair team handles everything from valve replacements to full repipes — same-day service available.

If you live in the Phoenix area, schedule your appointment with JB Water today. We’ll send over a certified plumber who can replace your leaky valve in no time.