Main Water Shut-Off Valve Upgrade
Updated February 20, 2026
Your main water shutoff is the single most important valve in your house. If a pipe bursts or a fixture fails, this is the valve that stops the flood. And in a lot of homes, it's a 30-year-old gate valve that barely turns. Upgrading to a full-port ball valve is one of the best investments you can make -- it gives you a reliable, instant shutoff that actually works when you need it most.
Overview
Your main water shutoff is the single most important valve in your house. If a pipe bursts or a fixture fails, this is the valve that stops the flood. And in a lot of homes, it's a 30-year-old gate valve that barely turns. Upgrading to a full-port ball valve is one of the best investments you can make -- it gives you a reliable, instant shutoff that actually works when you need it most.
What to Know
Tools & Materials
- Full-port ball valve (correct pipe size)
- Two pipe wrenches
- Pipe cutter or hacksaw
- Thread seal tape or pipe dope
- Union fittings
- Bucket and towels
- Meter key (if shutting off at the meter)
Step by Step
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Shut off at the meter
Locate the water meter (usually at the street or property line in a covered box). Use a meter key to turn the valve off. Verify by opening a faucet in the house -- no water should flow. If you can't find or operate the meter valve, call your water utility.
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Drain the system
Open the lowest faucet in the house and let the system drain. Open a few higher faucets too so air can enter and let the water flow out. You won't get all the water out, so have towels and a bucket at the work area.
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Remove the old valve
Cut the pipe on both sides of the old valve (or unscrew if threaded). Remove the old gate valve. Clean and prep the pipe ends.
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Install the new ball valve
Install union fittings on both sides for easy future access. Install the ball valve between the unions with the handle in the correct orientation. Use thread seal tape on all threaded connections.
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Turn water back on and test
Close the new ball valve. Turn the meter valve back on slowly to pressurize the system. Check every connection on the new valve for leaks. Then open the ball valve and run faucets throughout the house to purge air.
Pro Tips
- Get a full-port valve, not a standard-port. A full-port has a ball opening the same diameter as the pipe, so it doesn't restrict flow. Standard-port is cheaper but reduces flow.
- Add a drain valve (hose bib) just downstream of the main shutoff. This lets you drain the house piping quickly if you need to make repairs.
- Exercise the main shutoff annually -- turn it off and on once a year to keep it from seizing. This applies even to ball valves, though they're far less prone to it.
Mistakes to Avoid
- Not shutting off at the meter first -- you cannot replace the main shutoff with water flowing.
- Not installing union fittings, which makes future valve replacement require cutting pipe again.
- Buying a standard-port valve instead of full-port -- it restricts flow for the entire house.
- Forgetting to purge air from the system after the work is done.
When to Call a Pro
If you can't locate or operate the meter shutoff, if your supply line is lead or galvanized and crumbles when you touch it, or if local code requires a licensed plumber for work on the main supply -- call a pro. This is also a good job to hire out simply because a mistake on the main supply line affects the entire house.
Bottom Line
Upgrading the main shutoff to a full-port ball valve is one of the most important improvements you can make to your plumbing. A quarter-turn shutoff that actually works when you need it can be the difference between a minor incident and a major flood. $30-$80 in parts, well worth it.