By Gene and Katie Hamilton

The shutoff valve, which is also called a stop valve, controls the water flow to your faucets. Every faucet should have a shutoff valve at the hot and cold water supply lines so that when you fix a leak you don't have to shut down the entire water supply to the house. Having a shutoff valve is a good safety precaution too. With it, you can stop the flow of water at a faucet if there's an overflow.

A plumber charges $151 to replace two stop valves, which includes labor and material; but you can buy the valves and new flexible supply tubes for $25 and install them, saving 82 percent. You'll need basic plumbing tools like a basin wrench and an adjustable pipe wrench and, of course, a bucket.

There are two styles of valves used at sinks - a right-angle stop valve for when a water pipe enters through a wall, and a straight stop valve for when water enters through the floor. When shopping for shutoff valves, you should know what valve style you are replacing and what type of water pipes you have, plastic, copper or galvanized.

The Spruce describes more Types of Under Sink Shut Off Valves.

Now you know the average cost to install shutoff valves, which includes the labor and material, and what’s involved, so you can decide to do it yourself or hire a contractor. Don’t forget to adjust the cost to where you live by adding your ZIP Code.

Improvement and Repair Cost Updated 2017

The cost and time data is generated by averaging labor and material data from annually updated cost books used by contractors and refined by the authors' experience remodeling 13 houses. They are authors of 20 home improvement books and Do It Yourself or Not, a weekly column syndicated by Tribune Content Agency. The national cost can be adjusted by ZIP Code.