Burst Pipe Repair
Stop an active flood, then remove and replace the cracked or ice-split stretch of pipe. Open page
Plain-English article
Find and Close Your Main Water Shutoff in Thornton, CO
In a plumbing emergency, the main shutoff is the most important tool you have. Finding it takes a minute now and can save thousands later.
By the Thornton Plumbing Co. team ·
Where to look
With a basement, the main valve usually sits on the wall where the supply pipe comes in, frequently close to the water heater or the street side. In houses on slab or with a crawl space, it may be in a utility closet, a garage or a crawl space.
There is also a shutoff at the city meter, usually in a box in the yard or near the street. That one is for the utility, though a homeowner can use it in an emergency if the house valve fails. Ask the city what is allowed.
Types of valves
A gate valve works with a round wheel that spins many times, while a ball valve uses a lever that swings a quarter turn. The ball style tends to hold up better.
Turn a gate valve clockwise until it stops. Do not force it. For a ball valve, turn the lever so that it sits across the pipe.
Valve types
Know which one you have before you need it.
| Type | Handle | To close |
|---|---|---|
| Gate valve | Round wheel | Turn clockwise until it stops |
| Ball valve | Straight lever | Turn a quarter turn across the pipe |
| Meter valve | Flat stem or lever | Utility use, ask the city |
Test it twice a year
Turn the valve off and on again. A valve that is never used can seize with mineral scale. Hard water makes this more likely, and Thornton's water averages around 13.5 grains.
If it is stiff, never force it. A plumber can swap out a gate valve with a quarter turn valve in a short visit.
After you shut it off
Turn on a low tap to drain the lines and lower the pressure. Open a high faucet to let air in. Check the water heater, since turning off the cold supply also protects it.
If you turn the valve back on, open it slowly. A sudden surge can stress pipes and fixtures. Check for leaks at fittings and under sinks.
If the valve will not turn or leaks
A valve that will not close, or that drips from the stem, needs replacement. In an emergency, use the shutoff at the meter if the city allows it, and call.
Replacing the main valve requires shutting off water at the meter. A plumber can coordinate. See water line repair.
Label it
Tie a tag to the valve and tell everyone in the house where it is. Keep a wrench or a meter key nearby if your system uses one. Take a photo and save it in your phone.
Know where your electrical panel and gas shutoff are, too. For leaks, see burst pipe repair.
Finding the main shutoff
In most houses the water line enters at the front, beside the water heater or utility room, where a valve sits just inside the wall, often close to a pressure regulator. In houses with a basement, look on the wall closest to the street. In houses on a slab, check a garage wall, a closet or the laundry room.
There may be a second valve outside, at the meter pit, which belongs to the city. Do not operate the utility's shutoff unless you must, since it is their equipment. The valve on the house side is the one that is yours.
Two kinds of valve
A gate valve has a wheel-shaped handle which you turn clockwise to close, many times. Over the years the internal parts corrode, and a gate valve can fail to close or break when forced. A ball valve has a lever handle, and a quarter turn across the pipe closes it. Many plumbers replace a gate valve with a ball valve for that reason.
Turn the valve gently, and do not force a stuck handle. If it does not budge, call the 24/7 line and describe what you have tried, and shut off at the street meter only if you have to.
After you close it
Turn on the lowest tap in the house to empty the pipes. Open the highest to let air in. If a pipe has split, this drains the lines and stops the leak. Check that the water heater is not firing with no water. For an electric heater, switch off the breaker, and For a gas heater, turn the control to pilot or off.
Write down what happened and photograph any damage. If water is already on the floor, see water damage restoration for the next steps.
Test the valve once a year
Turn the main off and on a little once a year, so it does not seize. If it drips at the stem, the packing may need tightening or a replacement. Tell everyone in the house where it is and how it turns, because the person home when a pipe bursts is often not the one who knows. A label on the wall helps.
If the valve will not close
A valve that spins without stopping the flow has a worn stem or a broken gate inside. Do not keep forcing it. Look for a second valve upstream, such as the one at the meter, and call the 24/7 line so a dispatcher can route the call. The city can shut off a service at the street if needed, and the plumber can replace the valve once the water is off.
Replacing a failed main shutoff is a routine repair and a smart one. It is better done on a calm weekday than during a flood.
Quick answers
Asked about main water valve
Usually where the line enters the house, commonly in a basement or a utility room.
Clockwise for a gate valve, and a quarter turn across the pipe for a ball valve.
Do not force it. Use the meter shutoff if allowed and call a plumber.
In winter, many people do. It protects against burst pipes.
Connected services
Water Line Repair & Replacement
Mend or renew the buried pipe between the city's meter and your foundation when it breaks or corrodes. Open page
Leak Detection
Pinpoint where water is escaping inside walls, beneath floors or along the buried line before anything is opened up. Open page
Related reading
Tracking down a hidden leak
Reading the meter, dyeing the toilet tank and walking each room will turn up most leaks. Here is the order to do them in. Open page
How to thaw frozen pipes
A frozen pipe is a warning, not yet a flood. Here is how to thaw one safely, when to stop and what to do if it splits. Open page
Water heater leaking from the bottom
Pooling beneath a tank might trace to a fitting, a valve or a dead tank. Learn how to tell which, and what to do first. Open page
Water running and the valve stuck?
Phone the 24/7 line now and tell the dispatcher the main will not close.