What creates water pressure in the house?

Answer 1

High water pressure from the street or well, but there's an exception:

City water pressure (from the street) may need to have the pressure reduced to the home. Some homes have pressure regulators for this purpose, some do not. The same goes for well systems that use a pressure pump (an often a pressure tank); the outlet pressure is set so that the pressure to the home doesn't go too high or too low.

An exception for homes with fire sprinkler systems. There is a check valve from the main water supply that feeds the fire sprinkler system. As temperatures drop at night, the water in the fire sprinkler pipes contracts slightly and additional water from the main water line goes into the fire sprinkler system. During the day, the water in the fire sprinkler pipes heats up and expands slightly, but has no where to go because of the check valve. This action can cause a very high pressure in the fire sprinkler pipes if there isn't also a pressure relief valve in the system. Numerous older homes do not have a pressure relief valve for the fire sprinkler system and risk having a pipe or joint burst.

The bottom line: if you suspect that you have high water pressure in the home, consult a local plumber or building contractor for the appropriate solution.

Answer 2

Low pressure coming into the house. Pressure regulator on the line where it enters the house. Old pipes full of buildup. Screens on faucets clogged.