Weak water pressure makes everything harder — showers feel inadequate, dishwashers take longer, and filling a pot takes forever. The cause could be something you can fix in five minutes, or it could be a sign of a deeper plumbing issue.
Here are the six most common causes of low water pressure in a home, and what to do about each one.
First: How to Tell If It's Your Home or the Supply
Before assuming the problem is inside your home, check with a neighbor or two. If they are also experiencing low pressure, the issue may be with your municipal water supply — in which case, contact your water utility. If the problem is isolated to your home, one of the causes below is likely responsible.
Normal home water pressure is typically between 40 and 80 psi (pounds per square inch). If you want to check yours, a pressure gauge screws onto a hose bib (outdoor faucet) and costs about $10–$15 at any hardware store.
Cause 1: Clogged Aerator or Showerhead
What it is: Faucet aerators — the small mesh screens screwed onto the tip of every faucet — and showerhead nozzles trap mineral deposits over time. In areas with hard water, these can become significantly blocked within a year or two.
How to check: If only one or two fixtures have low pressure (while others are fine), the aerator or showerhead is almost certainly the culprit.
DIY fix: Unscrew the aerator or showerhead, soak it in white vinegar for 30 minutes to an hour, scrub gently with an old toothbrush, and reinstall. If it is too corroded to clean, a replacement aerator costs under $5 and takes two minutes to swap.
Cost: Under $10 if DIY.
Cause 2: Partially Closed Shutoff Valve
What it is: Your home has at least two main shutoff valves — one near the water meter at the street and one where the main line enters your home. If either was partially closed during a repair and not fully reopened, your entire home's pressure will be reduced.
How to check: Find both shutoff valves and make sure they are fully open. A ball valve is fully open when the handle is parallel to the pipe. A gate valve (wheel-type) is fully open when turned all the way counterclockwise.
DIY fix: Simply open the valve completely.
Cost: Free.
Cause 3: Faulty Pressure Regulator
What it is: Most homes built after the 1960s have a bell-shaped pressure regulator (also called a pressure reducing valve or PRV) near where the main water line enters the house. It is pre-set at the factory, typically to 50–80 psi. When it fails, it can cause pressure to drop sharply across the entire house.
How to check: If pressure dropped suddenly across your whole home — not gradually — a failed PRV is a likely cause. You can test the line pressure with a gauge.
DIY fix: Possible to replace yourself if you are comfortable with basic plumbing, but most homeowners call a plumber. Replacement costs roughly $250 to $600 installed depending on your area.
Cost: $250–$600 with a licensed plumber.
Cause 4: Mineral Buildup Inside Pipes
What it is: In homes with hard water, calcium and magnesium deposits gradually accumulate on the inside walls of pipes, slowly narrowing the channel water flows through. This is especially common in older galvanized steel pipes, which can become severely constricted over decades.
How to check: If your home is over 30 years old and still has galvanized pipes, and pressure has declined gradually over years (not suddenly), internal buildup is a likely contributor.
DIY fix: Not practical — pipe replacement is the solution once buildup is severe.
Professional fix: Pipe replacement (repiping) is a significant project, but targeted section replacement may be possible for isolated problem areas. Cost varies widely by the scope of work and your home's size.
Cause 5: A Leak Somewhere in the System
What it is: Even a small leak in a supply line — inside a wall, under a slab, or in the yard — bleeds pressure out of the system before it reaches your fixtures.
How to check: Turn off all water in your home and read your water meter. Wait 15–20 minutes without using any water, then read it again. If the meter moved, you have a leak somewhere.
Fix: Call a licensed plumber to locate and repair the leak. Depending on the location, this could be a minor repair or a more involved project (especially if it involves a slab leak — see our guide on slab leak signs and repair costs).
Cause 6: Corroded or Failing Pipes
What it is: Older galvanized steel pipes corrode from the inside out. As rust and scale build up, water flow decreases. This can cause low pressure in specific areas of the home served by affected runs of pipe, or throughout the home in severe cases.
How to check: If your home was built before 1960 and still has its original galvanized steel pipes, internal corrosion is a real possibility — especially if you also notice rust-colored water.
Fix: Section or full-home repiping by a licensed plumber. This is a significant project but eliminates the root cause rather than treating symptoms.
When to Call a Licensed Plumber
Call a plumber when:
- Low pressure affects your whole house suddenly — this suggests a PRV failure or main line leak.
- Your water meter moves when all water is off — confirms a leak.
- You have galvanized pipes and are experiencing gradual pressure loss — a plumber can assess whether section replacement or full repiping makes sense.
- Multiple DIY checks haven't resolved the issue — pressure problems can have more than one cause, and a professional can diagnose the full picture.
Find a licensed plumber near you to get a pressure assessment for your home.
Key Takeaways
- Low pressure in one fixture: usually a clogged aerator or showerhead — a quick, free DIY fix.
- Low pressure throughout the house: check shutoff valves first (free fix), then consider the pressure regulator, a leak, or pipe corrosion.
- A suddenly pressure drop across the whole home warrants a plumber call — likely a PRV failure or an active leak.
- Homes with galvanized pipes over 30 years old should have a plumber assess whether repiping is appropriate.
- Normal home water pressure is 40 to 80 psi — a $10 gauge from the hardware store lets you measure yours.
Sources & References
- https://www.smithsplumbingservice.com/blog/2025/january/the-most-common-causes-of-low-water-pressure-and/
- https://pugetsoundplumbing.com/blog/6-causes-of-low-water-pressure-and-how-to-fix-them/
- https://cycloneplumbingusa.com/low-water-pressure-causes-solutions/
- https://www.cardinalplumbingva.com/blog/most-common-causes-of-low-water-pressure-in-home/