Water enters your house through a main supply pipe connected to
a water utility main or to a source on your property.In most homes a water meter monitors usage from a water utility; a main shutoff valve (usually located near where the supply pipe enters the house) turns the water for the house on and off.
Once inside the house, the main supply pipe divides into two branches, one for hot water and one for cold. If the system is equipped with a water softner, it may be either on the main supply line before it divides or on the branch supply just the water heater.
For most of their distance, hot and cold water pipes run parallel and horizontally until they reach the vicinity of fixtures and water-using appliances. There, vertical branches, called risers, connect the fixtures or appliance to the water system.
Risers are usually concealed inside walls. Horizontal pipes are fastened to floor joists or buried under a concrete slab. Supply pipes, installed with a slight pitch in the runs, slope back toward the lowest [point so all pipes can be drained through a valve or faucet at that point. Some fixtures and water-using appliances have their own shutoff valves so you can shut off the water so it can be repaired without cutting off the water supply for the entire house. To be prepared for an emergency, everyone in the household should learn how to turn off the water supply both at the individual fixtures and at the main shutoff valve.
