Why Is My Water Pressure Low? 8 Causes and DIY Fixes
Weak showers and slow-filling fixtures are frustrating. Here's how to diagnose and fix common water pressure problems in your home.
Written by Illyrian Plumber
Expert ReviewedLicensed Master Plumbers
NJ Licensed Master Plumber | 10+ Years Experience | Serving Middlesex County, NJ
Few things are more annoying than stepping into a shower that barely trickles or waiting forever for a sink to fill. Low water pressure affects everything from your morning routine to how well your appliances work.
The good news? Many water pressure problems have simple solutions you can handle yourself. In this guide, we'll walk through the eight most common causes of low water pressure and show you how to diagnose and fix them -or know when it's time to call a professional.
About Illyrian Plumber
Licensed master plumbers specializing in high-end mechanical plumbing and water heating systems in Middlesex County, NJ. We offer tankless water heater installation, water heater repair, boiler repair, gas line services, and 24/7 emergency plumbing across East Brunswick, Edison, Sayreville, Old Bridge, Monroe Township, South Brunswick, and North Brunswick. 750+ projects completed since 2010.
Quick Diagnostic Questions
Is the problem in one fixture or the whole house?
One fixture = local problem (aerator, valve, supply line). Whole house = main line, PRV, or municipal issue.
Did the pressure drop suddenly or gradually?
Sudden = leak, valve issue, or municipal problem. Gradual = pipe corrosion or mineral buildup.
Is it hot water only or both hot and cold?
Hot only = water heater issue. Both = supply-side problem.
Clogged Aerators and Showerheads
The most common cause of low water pressure at a single faucet or showerhead is mineral buildup in the aerator or showerhead. Over time, calcium and other minerals deposit and restrict water flow.
How to Fix It
- 1. Unscrew the aerator from the faucet (turn counterclockwise) or remove the showerhead
- 2. Soak in white vinegar for 2-4 hours or overnight for heavy buildup
- 3. Use an old toothbrush to scrub away loosened deposits
- 4. Rinse thoroughly and reinstall
- 5. Run water to flush any remaining debris
Prevention tip: Clean aerators and showerheads every 6-12 months, especially in hard water areas like Middlesex County.
Partially Closed Shutoff Valves
If someone recently worked on your plumbing, a shutoff valve may not have been fully reopened. Even a slightly closed valve can significantly reduce water pressure.
Valves to Check
Main Water Shutoff
Located where the main water line enters your home (often in the basement or utility room). Wheel-style valves should be turned fully counterclockwise. Lever-style should be parallel to the pipe.
Street-Side Shutoff (Curb Stop)
Located near the street in a covered box. If your main valve is fully open but pressure is low, this could be partially closed. This usually requires a special key and may need the water company.
Individual Fixture Shutoffs
Found under sinks and behind toilets. If only one fixture has low pressure, check its local shutoff valves.
Pressure Reducing Valve (PRV) Issues
Most homes have a pressure reducing valve (PRV) where the main water line enters. This bell-shaped device reduces municipal pressure (often 80-100+ PSI) to a safe level for your plumbing (40-60 PSI). If the PRV fails or is set too low, you'll have low pressure throughout the house.
The PRV is typically located where the main water line enters your home.
Testing & Adjusting Your PRV
- 1. Buy a water pressure gauge ($10-15 at hardware stores)
- 2. Attach to an outdoor hose bib or laundry faucet
- 3. Turn on fully -ideal reading is 40-60 PSI
- 4. If low, locate the PRV (bell-shaped, on main line)
- 5. Use a wrench to loosen the locknut
- 6. Turn the adjustment screw clockwise to increase pressure
- 7. Adjust in small increments, testing between adjustments
- 8. Don't exceed 60-65 PSI to protect your plumbing
When to Replace the PRV
PRVs typically last 10-15 years. If adjusting doesn't help, or if you notice pressure fluctuations, the PRV may need replacement. This is a job for a licensed plumber -improper installation can cause pressure surges that damage fixtures and appliances.
Can't solve your pressure problem?
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Water Leaks
A leak anywhere in your plumbing system -especially in the main line -diverts water away from your fixtures, reducing pressure throughout the house.
Signs of a Hidden Leak
Simple Leak Test
Turn off all water-using fixtures and appliances. Check your water meter. Wait 2 hours without using any water. Check the meter again. If it has moved, you likely have a leak.
Learn About Our Leak Detection Services →Corroded or Clogged Pipes
Older homes with galvanized steel pipes commonly experience low water pressure due to internal corrosion and mineral buildup. Over decades, the inside diameter of these pipes narrows significantly, restricting water flow.
Signs of Pipe Corrosion
- • Gradually worsening water pressure over years
- • Discolored water (brownish, especially when first turning on)
- • Visible corrosion on exposed pipe sections
- • Home built before 1970 with original plumbing
- • Pinhole leaks developing in pipes
The Solution: Whole House Repiping
If galvanized pipe corrosion is causing your low pressure, the only permanent solution is replacing the pipes -typically with modern PEX or copper. While this is a significant investment, it solves the pressure problem permanently and eliminates the risk of pipe failure.
Learn About Whole House Repiping →Water Heater Problems
If low pressure affects only your hot water (cold water is fine), the problem is with your water heater or hot water lines specifically.
Sediment Buildup
Sediment accumulating at the bottom of the tank can restrict water flow. Annual flushing helps prevent this. For tankless units, the inlet filter may be clogged.
Partially Closed Hot Water Valve
Check that the hot water outlet valve on the water heater is fully open. Also check any shutoff valves on the hot water lines.
Corroded Hot Water Pipes
Hot water pipes corrode faster than cold water pipes. If only hot water pressure is affected in an older home, the hot water lines may need replacement.
Municipal Supply Issues
Sometimes the problem isn't in your home at all. Municipal water supply issues can cause low pressure throughout a neighborhood.
Municipal Causes of Low Pressure
- • Water main breaks or leaks
- • Fire hydrant use in the area
- • Water main maintenance or flushing
- • Pressure issues at the pumping station
- • High demand during heat waves
- • Your location relative to the water tower
What to Do
Ask your neighbors if they're experiencing the same issue. If so, contact your water utility. In Middlesex County, most areas are served by Middlesex Water Company or NJ American Water. They can tell you if there are known issues and when pressure should return to normal.
Peak Usage Times
Water pressure naturally drops during high-demand times -both within your home and throughout your neighborhood.
In Your Home
Running multiple fixtures simultaneously divides available flow. Shower while the dishwasher runs and someone flushes? Pressure drops.
Neighborhood-Wide
Pressure may dip during morning showers (6-8am) and evening cooking (5-7pm) when the whole neighborhood demands water.
Solution: If peak-time pressure drops are severe, a pressure booster pump can help maintain consistent pressure. However, make sure peak usage is actually the cause before investing in equipment.
Can't solve your pressure problem?
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Related Service: Water Leak Detection
Professional leak detection and water pressure diagnostics. We pinpoint the exact cause and provide cost-effective solutions.
Learn MoreMiddlesex County Considerations
Hard Water Buildup
Middlesex County's moderately hard water (7-10 grains per gallon) accelerates mineral buildup in aerators, showerheads, and pipes. Regular cleaning and considering a water softener can help maintain good pressure.
Older Homes
Many Middlesex County homes were built in the 1950s-1970s with galvanized steel pipes. If your home is 50+ years old with original plumbing, pipe corrosion is likely contributing to low pressure. Repiping may be the long-term solution.
Water Utility Contacts
For municipal water supply issues, contact Middlesex Water Company (most of East Brunswick, Edison) or NJ American Water (some areas). They can verify if there are main breaks or scheduled maintenance affecting your area.
Frequently Asked Questions
Why is my water pressure suddenly low?
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Sudden low water pressure is often caused by a water main break, a leak in your home, a closed or partially closed shutoff valve, or municipal water supply issues. Check with neighbors -if they're affected too, it's likely a municipal issue. If only your home is affected, check for leaks or valve issues.
What is normal water pressure for a house?
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Normal residential water pressure is 40-60 PSI, with 50 PSI being ideal. Below 40 PSI, you'll notice weak flow at fixtures. Above 80 PSI can damage pipes, fixtures, and appliances over time. You can measure your pressure with a $10-15 pressure gauge from any hardware store.
Why is only my hot water pressure low?
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Low hot water pressure specifically indicates a problem with your water heater or hot water lines. Common causes include sediment buildup in the water heater, a partially closed hot water shutoff valve, a clogged inlet filter (tankless units), or corroded hot water pipes.
How can I increase water pressure in my house?
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First, identify and fix the underlying cause. Clean aerators and showerheads. Check all shutoff valves are fully open. Adjust or replace your PRV if it's set too low. Fix any leaks. If you have old galvanized pipes, repiping is the permanent solution. For chronic low municipal pressure, a pressure booster pump is an option.
When should I call a plumber for low water pressure?
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Call a plumber if: you suspect a leak, cleaning aerators and checking valves didn't help, the problem affects the whole house, pressure has been declining gradually (suggesting pipe issues), you need PRV replacement, or you want a professional diagnosis. We can pinpoint the exact cause and recommend the most cost-effective solution.
Can't Solve Your Pressure Problem?
If DIY troubleshooting hasn't restored your water pressure, we can help. Our licensed plumbers will diagnose the exact cause and recommend the most effective, cost-efficient solution for your home.