Water Supply

Either a well, municipality, or a utility company supplies your potable (drinking) water. If you have a well, water is pumped from the well by a motorized pump into a pressure tank, and then into a supply system. When demand in the house causes pressure in the tank to drop, the pump turns on and water is drawn out of the well to refill the tank. The pump shuts off automatically when the pressure is re-established.

Water flows into most homes through a water service line at a pressure of 20 to 80 pounds per square inch (psi). Typical psi is between 25 and 50. A main shut-off valve is usually installed on the line near where it enters the building. You should know where the valve is located because you may need to shut off your water supply if you have a leak or are having plumbing work done.

Once inside the house, the pipe may connect to the water softener (if you have one) and then to the water heater. From the water heater, the piping branches out horizontally and vertically to fixtures such as tubs, toilets, showers, and sinks.

Horizontal pipes may be installed on a slight decline so that, in case of power failures or major repairs, the entire system can be drained through a valve at its lowest point.

Supply pipes are sometimes designed with air chambers, which act as "shock absorbers" when faucets are rapidly turned off. Without these, the system could develop ruptures from the pressure created by water flow being abruptly stopped. Sometimes these chambers become filled with water and you will hear banging in the pipes, known as "water hammer." If the banging persists, the air chambers can be re-established by a plumber or a handy homeowner with the aid of a repair manual.

If your plumbing system is operating properly, water pressure should be consistent. For example, water coming out of an upstairs sink should not be significantly reduced when the bathtub is running simultaneously. Sometimes, even if water pressure is in the normal range, water flow can be diminished if mineral deposits have built up on the inside surface of pipes or in faucet nozzle screens. These screens should be periodically cleaned.

Most interior residential water supply systems use one or more of the following materials for piping: galvanized iron, copper, brass, lead, or plastic. If your piping is lead, you may want to have your water laboratory-tested to determine if the lead is contaminating your water supply.

Regardless of the material used, all piping systems must be adequately supported by or attached to the studs or joists with compatible hangers, clamps, or other approved devices.