A curb stop is the water utility's shutoff valve for one property. It sits underground near the property line, inside a small curb box, and is turned with a long tool called a curb key. The utility uses it to shut off a home's water without affecting the street main.
A curb stop is the water utility's shutoff valve for a single property. It sits underground near the property line, at or before the water meter. The utility uses it to turn a home's water on or off without touching the street main. Plumbers also call it a curb valve or curb cock.
Where it sits and how it works
The curb stop is buried in the service line, the pipe that runs from the street main, starting at the corporation stop tap, to the house. It sits at or near the property line, usually under a small cap by the sidewalk or curb. That cap is the curb box, also called a buffalo box or b-box. A worker opens the box and reaches down with a curb key, a long T-handled rod, to turn the valve. The box often marks the point where the utility's pipe meets the homeowner's pipe.
Who operates it
In most cities the water utility owns and operates the curb stop. It is the valve they use to shut off service for a leak, a repair, or unpaid bills. Many utilities ask customers not to touch it. A curb stop that breaks can flood the line and bring a repair bill. Rules vary by city, and some make the owner keep the box clear. Check with your local water provider before you operate one.
Not the same as your house shutoff
A curb stop is not your home's main valve or a fixture stop. Your main shutoff is usually in the garage, in a wall box, or where the line enters the house, and you can use it in an emergency. A fixture stop is the small valve under a sink or toilet. The curb stop sits further out, at the utility's end of the line, and is meant for the utility, not daily use.