Low water pressure is frustrating no matter where you live, but for homeowners on municipal (city) water, it can be especially confusing. If the city is supplying the water, shouldn’t pressure always be strong?
In reality, city water pressure problems are extremely common, and most have nothing to do with the municipal system itself. The cause is often inside the home, hidden, or slowly developing over time.
At Dierolf Plumbing and Water Treatment, we diagnose municipal water pressure issues across Southeastern Pennsylvania every week. In most cases, the problem comes down to predictable components that fail gradually, not sudden catastrophic events.
Below are the 7 most common causes of low water pressure on city water, what’s really happening, and how the issue is correctly fixed.
1. Failing Pressure-Reducing Valve (PRV)
A pressure-reducing valve protects your home from excessively high street pressure. Over time, PRVs wear internally and slowly drift downward, reducing household pressure without ever “breaking.”
The International Association of Certified Home Inspectors explains that PRVs commonly fail by gradually lowering pressure as internal springs and diaphragms wear out.
Common signs
- Pressure slowly getting worse over months or years
- Pressure is low at all fixtures
- No visible leaks or obvious failures
What actually fixes it
Testing incoming street pressure and comparing it to regulated pressure. A failing PRV must be replaced to restore proper flow.
2. Corroded or Galvanized Piping
Many older homes still have galvanized steel pipes. Even when city pressure is strong, internal corrosion and scale buildup restrict flow, acting like plaque inside an artery.
The U.S. Environmental Protection Agency explains how galvanized pipes corrode internally over time, reducing water flow and contributing to pressure loss.
Common signs
- Pressure varies by fixture
- Rust-colored water
- Chronic pressure decline in older homes
What actually fixes it
Evaluating pipe materials and planning targeted repiping where restrictions are severe.
3. Municipal Supply Limitations
Sometimes the issue truly is external. Municipal systems experience pressure fluctuations during high-demand periods, fire protection use, or scheduled maintenance.
The American Water Works Association outlines how municipal distribution systems manage pressure zones and demand cycles.
Common signs
- Pressure drops at peak times (morning, evening)
- Issues worsen during summer
- Pressure returns later in the day
What actually fixes it
Confirming whether the issue is system-wide or home-specific, then adjusting household pressure regulation or storage if needed.
4. Partially Closed Meter or Main Valve
This happens more often than homeowners realize. After plumbing or utility work, the main shutoff or meter valve may not be fully reopened, restricting flow to the entire home.
The American Society of Home Inspectors identifies partially closed main valves as a frequent cause of low pressure discovered during inspections.
Common signs
- Sudden pressure drop after recent work
- Consistent low pressure throughout the house
What actually fixes it
Physically verifying that all main and meter valves are fully open.
5. Fixture-Level Restrictions
If low pressure is isolated to specific sinks or showers, the issue is often localized. Aerators, shower cartridges, and angle stops clog with debris or mineral scale.
Family Handyman provides a clear breakdown of how fixture-level restrictions reduce pressure at individual outlets.
Common signs
- One shower or faucet is weak
- Pressure improves when aerator is removed
What actually fixes it
Cleaning or replacing clogged aerators, cartridges, or shutoff valves.
6. Hidden Leaks
Underground, slab, or wall leaks reduce available pressure and volume before water ever reaches your fixtures. These leaks often go unnoticed for months.
The EPA explains that household leaks waste water and can significantly impact system performance and pressure.
Common signs
- Unexplained water bills
- Pressure slowly declining
- No visible leaks indoors
What actually fixes it
Professional leak detection and targeted repairs before structural damage occurs.
7. Undersized Service Line
Older homes were often built with smaller service lines that simply can’t meet modern water demand. Even with excellent city pressure, flow becomes limited at the point of entry.
Engineering Toolbox demonstrates how pipe diameter directly impacts flow capacity.
Common signs
- Pressure drops when multiple fixtures run
- No improvement after PRV or fixture repairs
What actually fixes it
Evaluating service line size and upgrading when flow demand exceeds capacity.
Why City Water Pressure Problems Are Often Misdiagnosed
Many homeowners are told the city is at fault or that “pressure is just low in the area.” In reality, most municipal pressure problems originate inside the home, not in the street.
In our experience evaluating city water systems, proper diagnosis prevents unnecessary pipe replacement, fixture upgrades, and frustration.
Schedule a Professional City Water Pressure Evaluation
If your home is connected to municipal water and pressure doesn’t feel right, guessing can lead to wasted money and missed problems.
Dierolf Plumbing and Water Treatment specializes in diagnosing city water pressure issues, including PRV testing, service line evaluation, leak detection, and fixture inspection. Our team helps homeowners get clear answers and reliable pressure without unnecessary repairs.
If you’re experiencing low water pressure on city water, a professional evaluation can identify the real cause and the right fix.
Frequently Asked Questions
Why is my city water pressure suddenly low?
Common causes include failing PRVs, partially closed valves, hidden leaks, or fixture restrictions.
Can a PRV really cause low pressure over time?
Yes. PRVs often fail gradually, reducing pressure without obvious signs.
Is low city water pressure dangerous?
It can be. Undetected leaks or excessive restriction can damage plumbing and increase costs.
Does replacing fixtures fix low pressure?
Only if the restriction is fixture-level. System-wide issues require deeper evaluation.
How often should city water pressure be checked?
Any time pressure changes noticeably or after plumbing work.
Proudly serving homeowners throughout Bucks County, Montgomery County, Chester County, Berks County, and surrounding Southeastern Pennsylvania communities.
