Why is my water pressure low only upstairs?

Most often piping restriction — corroded galvanized lines restrict flow, and upstairs fixtures are the longest run so they show it first. Occasionally it is a PRV set too low. A pressure test at the hose bib tells us which.

Can I adjust the pressure regulator myself?

PRVs have an adjustment screw, but a failing PRV does not hold adjustment — and over-pressurizing the house damages fixtures and appliances. If a gentle adjustment does not hold, replace it.

Is low water pressure a sign of a serious problem?

Usually not urgent — but a sudden drop, or pressure loss plus a running meter, can mean a supply leak that is actively damaging the house. That one is same-day.

Low Water Pressure? Causes & Fixes

One fixture or the whole house? That splits the diagnosis

One faucet or shower — almost always local: a clogged aerator, a worn cartridge, or a partially closed stop valve under the sink. Unscrew the aerator screen and rinse it; that fixes a surprising number of these calls for free.

The whole house — the problem is upstream: the main shutoff, the pressure-reducing valve, the supply line, or the piping itself. Different fix entirely.

Check these first

The main shutoff valve — if work was done recently, the main may have been reopened only partway. It should be fully open
Hot vs cold — low pressure on hot only points at the water heater side: a failing shutoff on the heater, or sediment. See our water heater guide
Neighbors — if the whole street dropped, it is the utility. A quick check saves a service call

The pressure-reducing valve (PRV)

Most homes have a bell-shaped valve where the main line enters — it knocks street pressure down to a safe range. PRVs fail gradually: pressure creeps down over months, or suddenly tanks. A plumber tests pressure at the hose bib, compares it against the PRV setting, and can swap a failed one in about an hour. Typical PRV life is 10–15 years.

The bigger one: corroded galvanized pipes

A lot of the pre-war housing stock in the older boroughs — Lansdale, Norristown, Pottstown, Reading — still runs galvanized steel water lines. Galvanized pipe corrodes from the inside: the bore closes down over decades until pressure drops and rust-colored water shows up. No valve adjustment fixes a pipe that is 80% closed — that is a repipe conversation, partial or whole-house depending on what is actually galvanized.

Clues you are looking at galvanized lines: gray magnetic pipe in the basement, pressure worst on upper floors, pressure that drops hard when two fixtures run at once.

The leak you cannot see

A hidden supply leak — slab, crawlspace, or an underground service line — drains pressure constantly. Quick check: shut off every fixture and watch the water meter. If the dial still moves, water is going somewhere it should not. A sudden pressure drop plus an unexplained meter reading is a call-today problem, not a monitor-it problem.

When to call

Whole-house low pressure that a fully open main valve does not fix
Rust-colored water or pressure collapsing when multiple fixtures run
The meter moving with everything off — that is a leak, and leaks get worse

Call or text (267) 227-8115. We diagnose the actual chokepoint before recommending work — see our plumbing repairs page.

Low water pressure? Figure out where it starts.