Plumbing Systems

Basics

If you've ever lived without plumbing, even for a weekend camping trip, you can appreciate how important it has become to modern living. Drinking water, baths, showers, toilets, dishwashers, clothes washers, gardens -- none of these are possible, or at least practical, without plumbing systems.

A house has several plumbing systems. Water supply piping brings water to the house and distributes it to fixtures and appliances, including outdoor sprinklers and irrigation. Drain and waste plumbing disposes used water and waste. Vent piping exhausts sewer gases and provides proper pressure for the drainpipes. Gas piping delivers fuel to gas-fired appliances. Some homes have pipe systems that serve specialty needs-swimming pool plumbing and built-in vacuum piping, for example.

Water supply plumbing delivers fresh water to all fixtures and appliances that require it; inside the house, the supply is split into two runs at the water heater. In some homes, the hot water line is connected to a water softener. Cold water typically is piped directly to all appliances and fixtures. A drain-waste-vent (DWV) system collects waste water from fixtures and waste from toilets and delivers them to a sewer or septic system. Vent pipes exhaust sewer gases and provide air pressure so wastes can flow freely.

Plumbing systems are composed of pipes and fittings. Metal or plastic pipes are joined by a variety of fittings designed to couple lengths in a straight line, turn corners, branch in two directions, reduce or enlarge pipe size, or connect to some type of fixture. Pipes are made from several different metals and plastics. You often can identify a pipe's purpose by its size and makeup: indoor water supply pipes generally are copper or galvanized iron pipe.

Water travels under pressure through a system of pipes to your home. You can trace the route of municipal water from the street to your house. The water company uses a meter to measure how much water you use, unless you use a well and your water use isn't tracked. This meter is often buried in a housing with a removable lid, located in front of the house near the street. In cold-winter areas, it may be inside the basement or crawl space, often placed where the meter reader can check it monthly without disturbing you. The water service delivers water to the meter through a large pipe called a main, which is often parallel to the street.

Once it passes through the main and meter, the water is controlled at different locations in your home with various types of valves, including the gate valve, the globe valve, and the hose bibb.

A main shutoff valve, a gate valve, is often located on each side of the water meter. The one on the street side is the water company's valve, which shuts off the system when work is being done on it or your meter is being changed. The other valve controls water that flows to your house. This is the main shutoff. Turn it completely clockwise to stop all water from flowing through your water supply system-both indoors and outdoors. The water meter measures the amount of water that is used in your house. The meter uses dials or a digital readout to record how many cubic feet of water travel through it. The service's meter reader records the numbers each month and the company computes the difference between last month's and this month's readings to figure your bill. Reading a digital meter is easy-just like reading a car's odometer. To read a dial-type meter, record the smallest of the two numbers near the tip of each needle.

Two separate networks deliver water throughout a house-cold water and hot water pipes. They usually run in tandem, branching off to serve faucets, fixtures, and appliances. The cold water pipes carry water from the water service to all fixtures and appliances, including the water heater. In some cases, outdoor faucets and irrigation systems are fed by the cold water pipe before it reaches the house. Hot water pipes, which originate at the hot water heater, serve only those fixtures and appliances that require hot water; they don't, for example, go to the toilet.

The water in the pipes is under relatively high pressure. The pipes must be strong enough to handle the pressure, and their fittings and connections must be secure enough not to leak.