Home water pipes deliver pressurized water from the municipal supply or well through a main line into your house. The main line splits into cold and hot water branches with hot water routing through the water heater. Pipes are typically copper PEX or CPVC with diameters ranging from half inch to one inch. Water pressure is maintained between 40 to 80 PSI. Drain pipes use gravity to carry wastewater downward to the sewer or septic system.