Water Pressure
The force that pushes water through your pipes and out of fixtures, measured in pounds per square inch (PSI) and ideally sitting between 40 and 60 PSI in a home.
Water pressure is what makes a shower feel strong and fills a washing machine in a reasonable time. It comes from the municipal main or, on a well, from a pump and pressure tank. Most residential plumbing is designed to run on 40 to 60 PSI. Below about 40 the system feels weak, especially when two fixtures run at once. Above 80 PSI you are in territory that stresses valves, hoses and seals, which is why code caps incoming pressure at 80 and a regulator is required when the street delivers more.
Homeowners usually notice pressure only when it changes. A sudden drop across the whole house points to the meter, a failing pressure reducing valve, or a leak between the street and the home. A drop at a single fixture is almost always local: a clogged aerator, a half-closed angle stop, or a corroded supply line. Telling whole-house from single-fixture is the first diagnostic step, because the two problems live in completely different price brackets.
Pressure and flow are related but not the same. Pressure is the push; flow (measured in gallons per minute) is how much actually moves. A pinhole-sized opening at high pressure still delivers a trickle, which is why old galvanized pipes can show normal pressure on a gauge yet starve a shower. Understanding the difference keeps you from replacing a regulator when the real culprit is decades of mineral scale narrowing the pipe.
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- Main Shutoff Valve : The valve that stops all water entering the house, typically located where the supply line comes through the wall near the meter or in the basement.
- Water Meter : The utility-owned device that measures how much water your home uses, usually located at the property line in a buried box or in the basement.
- Angle Stop / Fixture Shutoff : The small individual shutoff valve under a sink or behind a toilet that stops water to that one fixture without shutting down the whole house.