Low water pressure is one of the most common complaints we hear, and one of the most misdiagnosed. Before anyone sells you a booster pump, it is worth ten minutes of narrowing down where the problem actually is.
One Fixture, Or The Whole House?
One tap or shower: the problem is at the fixture. A clogged aerator, a scaled shower head, or a cartridge full of debris. These are quick fixes.
Hot side only: the water heater or the hot supply piping. Sediment in the tank, a failing dip tube, or a partially closed valve on the hot outlet.
Everywhere, all the time: the main supply. That points to the pressure-reducing valve, the main shut-off, the service line, or old galvanized pipe.
The Pressure-Reducing Valve
Most homes on municipal water in the Lower Mainland have a pressure-reducing valve (PRV) where the main enters the house, especially on hillside lots in Mission, Coquitlam, White Rock and Maple Ridge where street pressure runs high. PRVs wear out. When they fail they can drop the pressure well below the 40–60 psi a house should have, or let it creep up high enough to damage fixtures and appliances. A pressure gauge on an outside tap tells us in thirty seconds.
Galvanized Steel Pipe
Homes from before the 1960s in Burnaby, New Westminster, older Surrey and Langley often still have galvanized supply lines. They rust from the inside, and the opening narrows over decades until a half-inch pipe is passing water through a hole the size of a pencil. Pressure at the street is fine; flow at the tap is not. The fix is replacement, usually with PEX, and it is the single biggest improvement those houses can get.
Hidden Leaks
A sudden drop in pressure, a water bill that jumped, a warm spot on a slab floor or a meter that turns with everything off all point to a leak. Find it before it finds your drywall.
What We Check On A Pressure Call
- Static pressure at an outside tap, then pressure while a fixture runs
- The PRV and the main shut-off valve (a partially closed gate valve is a classic)
- The water heater and hot supply if only hot is weak
- Pipe material and condition at accessible points
- The meter for movement with the house shut off
Most low-pressure problems have one cause and one fix. The wrong fix is the expensive one.
Related: pipe replacement · residential plumbing services
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