Weak water pressure is one of the most common complaints we hear in Southern Utah — and hard water is often at the root. Here's how to pin down the cause before you call for help.
Few things test your patience like a shower that trickles or a faucet that can't fill a pot in under a minute. Low water pressure has a handful of common causes, and in St. George one of them looms larger than anywhere else: some of the hardest water in the country. Before you assume the worst, here's how to narrow down what's actually behind it.
First, Is It the Whole House or One Fixture?
This is the single most useful question you can answer, because it splits the problem in half. Walk around and test a few taps. If pressure is weak everywhere — every sink, both showers, the hose bib outside — the cause is somewhere on your main line or regulator. If only one faucet or showerhead is weak while everything else runs strong, the problem is isolated to that fixture.
That one observation tells you whether you're looking at a quick, cheap fix or something that affects the whole system. Start there before you go any further.
Hard Water Scale Narrowing Your Pipes
Southern Utah water runs 15 or more grains per gallon of hardness — among the hardest in the nation. Over years, the dissolved calcium and magnesium precipitate out and coat the inside of your pipes with mineral scale. That buildup slowly narrows the interior diameter of the pipe, and less open space means less flow reaching your fixtures.
This is a gradual, whole-house decline. If your pressure has faded slowly over years rather than dropping overnight, scale is a prime suspect — especially in a home that's never had water treatment. It's also why so many Southern Utah homeowners eventually add a softener: untreated hard water doesn't just hurt pressure, it shortens the life of every pipe, fixture, and appliance it touches.
Corroded Galvanized Pipe in Older Homes
Many older St. George homes were plumbed with galvanized steel pipe. From the inside out, that pipe corrodes and builds up rust and scale over decades, choking off flow the same way clogged arteries do. Once galvanized pipe reaches this stage, no amount of cleaning restores it — the metal itself is deteriorating.
If you're in an older home with original plumbing and pressure has gotten steadily worse throughout the house, aging galvanized pipe is often the culprit. This is usually a case where repiping is the real long-term answer.
A Failing Pressure Regulator
Most homes have a pressure-reducing valve where the main line enters, set to keep incoming municipal pressure at a safe level. When that regulator starts to fail, it can drift and choke down your pressure across the entire house — sometimes gradually, sometimes suddenly.
A failing regulator produces low pressure at every fixture at once, which is why the whole-house-versus-one-fixture test matters so much. A tech can measure your pressure directly and confirm whether the regulator is the problem.
A Hidden Leak
If water is escaping somewhere between the meter and your fixtures, less of it reaches the tap. A hidden leak — under a slab, behind a wall, or out in the yard line — can pull down pressure while quietly running up your water bill. Watch for damp spots, unexplained warm areas on the floor, or a meter that keeps ticking when everything is shut off.
Because leaks waste water and can damage your home, this is one cause you don't want to sit on. Professional leak detection can pinpoint the spot without tearing into walls to find it.
Clogged Faucet Aerators — the Easy One
If only one fixture is weak, start with the aerator — the little screen that screws onto the tip of the faucet. In our hard water, these clog with mineral flakes and grit surprisingly fast. Unscrew it, rinse out the debris, soak it in vinegar to dissolve the scale, and thread it back on. Same idea for a showerhead.
This is a five-minute, no-cost fix that solves a huge share of single-fixture complaints. Always rule it out before assuming anything bigger is wrong.
When to Call Marlin
If a quick aerator cleaning doesn't restore a single weak fixture, or if pressure is fading across the whole house, it's time to have it looked at properly. Our techs can run leak detection, test your regulator, and tell you honestly whether you're facing a simple repair or aging pipes that call for water main and line repair — or in older homes, a full repipe.
We've plumbed Southern Utah homes since 1978, and we know what this water does to a system over time. We'll find the real cause instead of guessing, and give you a straight answer on the fix.
Marlin Plumbing Heating & Air
Serving St. George, Utah since 1978