Key takeaways
- Pressure low at one fixture is that fixture; low everywhere points at the service line, a valve or a regulator.
- Meter moves with the house isolated: a leak. Meter still, pressure low everywhere: a restricted line or a valve.
- Old galvanized narrows from internal rust long before it leaks; rusty water after a shutoff is the tell.
- A new continuous service line often restores pressure the house hasn't had in decades.
Start by narrowing it
Run the kitchen tap, then a bathroom tap, then an outside hose bib near the point of entry. If only one is weak, the problem is that fixture or its branch and a plumber is the right call. If all of them are weak, including the hose bib closest to where the line enters, the problem is upstream of the house: the service line, the main shutoff, a pressure regulator if there is one, or on a well, the pump and pressure switch.
Check the valves
A main shutoff that was closed for a repair and never fully reopened is more common than anyone admits. Old gate valves also fail with the gate partly dropped, restricting flow while looking open. Confirm the house main shutoff and any valve on the house side of the meter are fully open. If there's a pressure regulator, it can fail closed or drift; a gauge on a hose bib tells you what pressure the house is actually getting.
The meter test
Everything closed, low-flow indicator watched, then the house isolated at the main shutoff. If the indicator moves with the house isolated, the service line is leaking, water is leaving before it reaches your fixtures, and an acoustic locate finds the break. If the indicator is still and the pressure is low everywhere, nothing is leaking; the line simply can't deliver flow.
The restricted line
A line that doesn't leak but can't deliver is almost always old galvanized steel. The zinc coating is gone, the steel has rusted, and the rust has built up inside until the bore is a fraction of its original size. Rusty water after the supply has been off is the classic sign. Bremerton's wartime housing, Keyport's village, Poulsbo's and Port Townsend's historic cores are full of it. The fix is a replacement line in continuous PEX or HDPE from the meter to the house, which restores full pressure and ends the rust.
On a well
Pressure that falls while the pump runs continuously is usually a leak on the buried line. Pressure that cycles up and down rapidly is a waterlogged tank. Pressure that's simply low with the pump cycling normally is often the pressure switch setting or a worn pump. We isolate the buried line at the tank to rule it in or out, and coordinate with your well company for the rest.
Written by the crew at 360 Leak Finders
We locate, excavate and repair buried water lines and exterior drains across Kitsap County, 24 hours a day. If this guide raised a question about your property, call (206) 354-9906.