Kitchen Plumbing Basics
This guide only talks about the plumbing commonly found in kitchens. In bathrooms the plumbing is more complicated, but many people call a professional to do the work in this part of their home.
In a typical kitchen, there are two plumbing systems that work together to met your needs. The first is the water supply system. The second is the drain-waste and vent systems. This system is commonly abbreviated as DVW. These pipes together are what is called the sink complex. The sink complex serves the combination of your sink plus other appliances such as a garbage disposal or dishwasher that use water.
Water that enters your house may come from a well or a public water main. As it enters the house, it is split into cold water pipes and hot water pipes. They often run parallel to one another, but the hot water pipes must be routed through the water heater before they reach your faucet. The pipes are often in your floor until they are needed to supply water. In that case, they are often run up through the interior of a wall. A wall with plumbing in it is called a wet wall. These types of pipes are the water supply system.
There is usually one valve in a kitchen that controls the water supply system for that room. Always turn off this valve when working on any of your water based kitchen appliances. Most valves are found under the sink.
There are two types of pipes that make up the DVW. The first, vent pipes, are used to maintain pressure in drainpipes and traps. They also carry away sewer gasses. Each house has a main pipe called a soil stack. A soil stack serves two purposes. Below the level of the fixture, the soil stack acts as a drain pipe, removing dirty water. The part above the fixtures goes through your roof and acts as a vent pipe.
Smaller drainpipes feed into the larger soil stack. In some cases, if the fixtures are far away from each other, another smaller soil stack may be constructed to service that part of the house.
In a normal kitchen, a set of vertical supply pipes and a single drain pipe makes up the sink complex. For the sake of economy, most fixtures that require water center around the sink. Supply pipes for items such as icemaker or a dishwasher come off the main lines. In a similar fashion, disposals and dishwashers will also share the main drain pipe.
If you are still having trouble understanding your plumbing and how the different pipes work together to provide water to your home, try this technique. Imagine the path of a single drop of water through your home. It should go from the public water pipe, to the hot water heater (if hot water), underneath the floorboards, and to be used in the sink. Draining out of the sink it will go into the drain pipe and be carried off to the sewage system.
By understanding the different parts of your home plumbing system you should be able to make simple repairs and adjustments yourself. If you are still unsure of how your plumbing system works, do not hesitate to call a professional to do small plumbing jobs. A plumber might not be cheap, but water damage is fairly expensive as well.
