How Your Home Plumbing System Works

If you're like many people across the country, your home's plumbing system seems complicated. But once you get to know some of the basics, the system is actually quite easy to understand.

Supply, drain, vent

These are the three main functions of the plumbing system in a typical home. The supply system supplies water to the house, dividing it into hot and cold water lines and sending it to all the fixtures in the house such as sinks, toilets, showers, and tubs. Water is also supplied to appliances that need it, such as washing machines, dishwashers, water heaters, and heated system boilers.

The drainage system, as the name implies, brings water away from all the fixtures in the house, while the vent system injects the drainpipes with air so that waste can be carried away. Drains and vents use the same type of pipes and are connected, so you'll often hear them referred to as the drain-waste-vent system or DWV.

Water meter

To become more familiar with your plumbing system, find out where the water meter and main shutoff is located. If you have metered water search for the place where water first enters the house, and you should find a water main (a pipe about an inch thick) in the floor of your basement or first floor. It should enter and exit a round gauge - this is the water meter. It will either be a digital readout or contain 5 or 6 dials. Not every house has a meter.

You should be able to find one or two valves near where the water enters your house - this is the main water shutoff. Some homes have another shutoff outside the house in something called a "buffalo box," or buried cavity. Near the street or edge of your property, try to find a round metal cover in the ground, perhaps underneath grass. Lift it up and peer inside with the aid of a flashlight. Depending on where you live, you may find a valve you can turn by hand, or it may require the use of a long-handled "key." In warmer climates many older homes actually have an exposed valve outside.

Especially in older homes, be aware that the inside shutoff may not be enough in the event of an emergency, as it can break, leak, or stop shutting off. During a renovation project, if you will have to shut off the water quite often, it's a good idea to know where the outside shutoff is located so that you can turn off your home's water system from there.

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