How much does it cost to fix low water pressure?

A pressure regulator replacement typically runs $200–$500. Full repiping in Sonoma County homes ranges from $4,000–$15,000 depending on size and pipe material. West Coast Plumbing provides free estimates.

Why is my water pressure low only in one bathroom?

Localized pressure issues typically point to a partially closed angle stop valve, a clogged aerator, or a failing fixture cartridge. If pressure is low throughout the house, the cause is upstream in your main supply lines.

Low Water Pressure in Your Sonoma County Home? Here’s What Causing It (And How to Fix It)

You turn on the shower and get a trickle. You run the dishwasher and the kitchen faucet goes limp. Low water pressure is one of the most common plumbing complaints we hear from homeowners across Sonoma, Marin, and Napa County. The good news: it almost always has a clear cause. Here's what to look for — and what to do about it.

First, Is It Just Your Home or the Whole Neighborhood?

Before calling a plumber, check with a neighbor. If everyone on your street has weak pressure, the issue is with your municipal water supply — not your pipes. Contact your local water district and wait it out.

If it's just your home, keep reading.

The 6 Most Common Causes of Low Water Pressure

A Partially Closed Shutoff Valve

Your home has a main shutoff valve — usually near the meter or where the water line enters the house. If it was ever partially closed during repairs and not fully reopened, your entire home runs at reduced pressure. Check it first. It's a two-second fix.

Clogged or Corroded Pipes

This is the big one — especially in older Sonoma County homes. Mineral-rich water deposits calcium and magnesium inside pipes over time. Those deposits narrow the pipe's interior and choke off flow. If your home has galvanized steel pipes, corrosion makes it even worse. You can't fix this with Drano. The solution is pipe replacement — or targeted descaling if the buildup is localized.

A Failing Pressure Regulator

Most homes have a pressure regulating valve (PRV) installed where the main line enters the house. It keeps water pressure in the safe 40–80 PSI range. When a PRV fails — and they typically last 7–12 years — it can drop your pressure significantly or cause it to fluctuate. A licensed plumber can test yours in minutes and replace it if needed.

Leaking Pipes

If water is escaping somewhere in your system — through a pinhole leak, a cracked joint, or a failed fitting — less of it reaches your faucets. Low pressure combined with an unexplained spike in your water bill is a strong signal that a hidden leak is involved.

Multiple Fixtures Running Simultaneously

Some older plumbing systems weren't designed for the demands of a modern household. If your pressure drops every time someone flushes while you're in the shower, you may have undersized supply lines. A repiping assessment can identify whether pipe diameter is the limiting factor.

Hot Water Only? Check Your Water Heater

If your cold water pressure is fine but hot water is weak, the problem is isolated to your water heater. Sediment buildup inside the tank is the likely culprit. A tank flush — or in older units, a full replacement — usually resolves it.

How Low Is Too Low?

Normal residential water pressure falls between 40 and 80 PSI. Below 40 PSI and you'll notice it. Below 30 PSI and basic tasks become a problem. A plumber can test your pressure in minutes with a gauge — worth knowing your number before assuming the worst.

When to Call West Coast Plumbing

Low water pressure is rarely an emergency — but it almost never resolves on its own. The underlying cause gets worse over time. Call us if:

Pressure has been dropping gradually over months
Only certain areas of the house are affected
Your water bill has gone up alongside the pressure drop
Your home was built before 1990 and still has original pipes
You've checked the shutoff valve and it's fully open
Hot water pressure is fine but cold is weak, or vice versa

We serve Sonoma, Marin, and Napa County homeowners — Santa Rosa, Petaluma, Healdsburg, and everywhere in between. Honest assessment, upfront pricing, no upsells. Request a free inspection →

Frequently Asked Questions

Common questions from North Bay homeowners about low water pressure.

Sudden pressure drops are usually caused by a main shutoff valve that was partially closed, a burst or leaking pipe, or a failing pressure regulator. If the drop is abrupt and severe, shut off your main water supply and call a plumber immediately.

Yes. Hard water leaves mineral deposits inside pipes over time. As those deposits accumulate, they narrow the interior diameter of the pipe and reduce flow. Sonoma County water is high in minerals, making this a common issue in older homes.

It depends on the cause. A pressure regulator replacement typically runs $200–$500. Pipe descaling or localized repair varies by scope. If full repiping is needed, most Sonoma County homes range from $4,000–$15,000 depending on size and pipe material. West Coast Plumbing provides free estimates — call (707) 750-9900.

Not immediately — but it can signal a hidden leak or pipe failure that becomes costly if left unaddressed. Pressure below 20 PSI can allow contaminants to back-siphon into your water supply, which is a real health concern. Get it diagnosed sooner rather than later.

Localized pressure issues usually point to a partially closed angle stop valve, a clogged faucet aerator, or a failing fixture cartridge. These are inexpensive fixes. If pressure is low throughout the house, the cause is upstream in your main supply lines.