PVC piping is relatively inexpensive to use for plumbing applications. It is also more easy to work with for future modifications if necessary. When PVC piping that supplies water to a sink, washer, water heater, or deep sink needs a shutoff valve for emergency purposes, it is not difficult to add to the pipe. You only need a few tools and no real plumbing experience.
Turn off the water supply to the PVC piping by securing the main water line into the house. There are typically two main line shutoff points: one near the curb by the street and the other on the exterior of the house, usually on the same side as the garage.
Cut out a small portion of the PVC pipe with a hacksaw. Cut a section slightly smaller than the length of the shutoff valve's vertical run. Leave enough room to insert a small part of each side of the PVC into the shutoff valve.
Insert the shutoff valve onto the PVC piping. Cover one end of the PVC piping with pipe dope and slide the shutoff valve onto it. Then, brush on pipe dope to the other connecting side of the PVC pipe and insert it into the shutoff valve. Allow the adhesive to dry according to the manufacturer's instructions printed on the can.
Test the valve. Turn on the main water line to the house in the same location you shut it off. Allow the water pressure to build for five to ten minutes. Go to the shutoff valve and inspect it for leaks and then turn it on and off to ensure it shuts the water flow off.