Basic Kitchen Sink Plumbing

A kitchen sink.

Understanding the basics of kitchen sink plumbing is a must for the avid do-it-yourself homeowner. Minor problems with basic plumbing are a common problem in even the most expensive and well-built homes. By tackling these repairs yourself, you can save hundreds of dollars in plumbing repair costs over the life of your home. To help simplify matters, we’ll separate basic kitchen sink plumbing into three sections: water supply, water drainage, and fixtures.

Water Supply

Domestic hot and water supply lines are a crucial part of your kitchen sink plumbing system. Individual 1/2-inch copper pipes deliver the hot and cold water to the sink. At the end of each of these supply lines are shut-off valves. These valves are soldered to the copper pipes and allow for you to shut off the water at the sink location without shutting down the main water supply. Shut-off valves are offered as two different types and are sized with either a 1/2-inch or 3/8-inch outlet for connecting to the fixture.

One type uses a threaded connection for the outlet and the other type uses a soldered connection for the outlet. The type of supply line from the valve to the fixture will be dictated by the type of shut-off valve you choose. The most common are flexible, braided supply lines that are used with threaded connections. These are found in varying lengths from 6 inches all the way up to 24 inches depending on your needs.

Water Drainage

The drainage portion of kitchen sink plumbing consists of 1½-inch diameter PVC piping that eventually makes its way to the main sanitary line out of the home. The sink that you purchase will come with the strainer body, rubber gasket, and locknut. From there, a straight piece of PVC piping is connected to the trap with a coupling. The trap is shaped like the letter “J” and usually contains a cleanout to remove clogs. From the trap, another coupling is used to connect another section of PVC piping to the waste piping within the wall.


The last and most visible portion of kitchen sink plumbing are the sink and fixtures. Kitchen sinks have a variety of options for the homeowner to choose from. One of the main differences is under-mount and surface mounted models. An undermount kitchen sink is installed under the countertop which eliminates the need for a flange. Sinks are constructed using either acrylic, composite, cast iron, or stainless steel materials. A standard sink has a depth of 6 inches but new “deep bowl” models are now available with a depth of 9 inches. Some models even separate the sink bowl into two compartments to separate cleaning and rinsing.

Kitchen sink fixtures are available in a wide variety of designs and styles from basic chrome-plated fixtures to ornate brass antique designs. It’s important to select the kitchen sink and fixture at the same time. For example, if you want a fixture that incorporates a spray hose then you’ll need to select the sink that has the correct number of access holes.