To test your main water shut-off valve, open a cold faucet, then close the main valve: a quarter turn for a ball valve, or clockwise until it stops for a gate valve. The faucet should slow and stop. Check the valve for drips, reopen it all the way, and repeat the test a couple of times a year.
Where is the main shut-off valve?
You can't test it until you find it. The City of Phoenix says that for most houses, "this valve is usually located at the front of the home, near a hose bib." Look for a pipe coming out of the ground and going into the house, with a valve, knob or switch on it. The city adds that some older houses have the valve at the rear of the property, and homes with basements may have it inside the basement or a crawlspace, on a wall facing the street.
Other Valley cities describe it differently, so check your own utility. Scottsdale, for example, tells property owners to know where the property owner's cut-off valve is and how to use it, and says "The valve is located adjacent to the water meter box."
If your water comes from a private water company regulated by the Arizona Corporation Commission, a state rule applies to new service. Where service is being provided for the first time, the customer must "provide and maintain a private cutoff valve within 18 inches of the meter on the customer's side of the meter," and the utility provides a like valve on its side (Ariz. Admin. Code R14-2-405).
For more help finding it, see where the main water shutoff is in a Phoenix home.
### Don't use the meter instead
Whatever you find, the valve in the meter box belongs to the water provider. Phoenix is direct about it: "It's important for you to NOT shut your water off at the meter. This requires a special tool and you may be held responsible for any repairs to a damaged water meter." If you can't find your house valve, the city says to call its Customer Services office and it will send a technician to turn the water off at the meter.
How do I test it, step by step?
Pick a time when nothing is wrong and nobody needs water for a few minutes. Let everyone in the house know what you're doing. Then work through these steps.
### 1. Identify the valve type
Look at the handle:
- A lever handle usually means a ball valve. It moves a quarter turn. The San Francisco Public Utilities Commission describes a ball valve handle "that turns off at a 90 degree angle to the supply pipe."
- A round wheel usually means a gate valve. It takes several turns. SFPUC says to turn an older-style gate valve's wheel or handle "clockwise until it stops."
Not sure which you have? Our page on the difference between a ball valve and a gate valve shows how to tell them apart.
### 2. Open a cold faucet
Turn on a cold tap inside the house to a steady stream. This is your gauge. When the main valve closes, this faucet should slow and stop.
### 3. Close the main valve
Close it firmly but gently:
- Ball valve: turn the lever a quarter turn until it sits across the pipe.
- Gate valve: turn the wheel clockwise until it stops. Don't use a wrench or a cheater bar on a wheel that won't move.
If the handle won't budge with normal hand pressure, stop here. Forcing a stuck valve can do more harm than good. Skip to the section on a failed test.
### 4. Watch the faucet
Water already in the pipes may keep flowing for a moment, so the stream may not stop instantly. It should taper off and stop. If it keeps running at a steady flow, the valve isn't closing all the way.
### 5. Check the valve for leaks
While it's closed, look at where the stem enters the valve body. InterNACHI, the home inspectors' association, tells inspectors to look for water leaks that may come from "the valve stem, packing washer, and packing nut," and suggests wiping the bottom of the valve body and looking for watermarks below it. A quick wipe with a dry rag tells you a lot.
### 6. Reopen it all the way
Now open the valve fully:
- Ball valve: turn the lever back so it lines up with the pipe.
- Gate valve: turn the wheel counterclockwise until it's fully open, then ease off. NIBCO's gate valve instructions say it is "not recommended valves be tightly back-seated as line contamination over a long period of time may lock up the valve causing problems when the valve has to be closed."
Make sure it's fully open. The City of Phoenix lists "A partially closed house valve" among the potential causes of reduced water pressure.
### 7. Close the faucet and check again
Let the faucet run until the air sputters out and the flow is steady, then turn it off. Take one last look at the valve for fresh drips.
What does a failed test look like, and what then?
Here are the usual failures and what each one means.
| What you see | What it likely means | What to do |
|---|---|---|
| Handle won't turn | Seized stem or buildup | Stop. Don't force it. Plan a replacement. |
| Faucet keeps running steadily | Valve no longer seals | Plan a replacement before you need it. |
| Drip at the stem after turning | Worn or loose packing | See why a shut-off valve leaks at the handle. |
| Pressure is low after the test | Valve not fully open | Reopen fully and check again. |
| Leak at the pipe connections | Joint or valve body problem | Call a plumber. |
A small drip at the stem is often fixable. NIBCO's ball valve manual says the packing nut under the handle can be tightened "in 1/8- to 1/4-turn increments, just enough to stop leakage."
A valve that won't close, or won't seal, needs replacing. That job requires turning the water off ahead of the valve, which in Phoenix means the city's side of the meter. Don't try it at the meter yourself.
### Won't a home inspection catch this?
Probably not. InterNACHI says "Inspectors should not turn the valve during a home inspection." Its standards ask the inspector to describe the valve's location and report any water leaks observed. So a clean inspection report tells you where the valve is, not whether it closes. Test it yourself soon after you move in.
How often should I test it?
Phoenix says to test it regularly but doesn't name a schedule. Manufacturers give a firmer number for their own valves. NIBCO says its ball valves "must be exercised from fully opened to fully closed periodically," and recommends a routine exercise program, "such as cycling at least once every 6 months."
Twice a year is easy to remember. Tie it to something you already do, like changing smoke alarm batteries or the start of summer and winter. Testing also helps the next emergency go smoothly, because everyone in the house will know where the valve is and how it turns.
If you're gone for long stretches, Phoenix's tips suggest that for long periods away from home, you shut off the water to your house and water heater. That's one more reason to know your valve works. Our yearly plumbing maintenance checklist has the rest of the seasonal list.
If your main valve fails the test, call HQ before the next emergency finds it for you. We're available 24/7, licensed and insured, and we give free estimates with upfront pricing.