Common Causes of Low Water Pressure

Low water pressure can result from various underlying issues and can affect a single fixture or your home’s entire plumbing system.

Can a plumbing leak cause low water pressure?

A plumbing leak can cause low water pressure by diverting water out of your system before it reaches a fixture, disrupting the usual flow rate. Major leaks or ruptured pipes have the most immediate impact and cause a system-wide drop in water pressure.

Slow or hidden leaks may not be as obvious as burst pipes, but even a trickle escaping from pipes continuously diverts water from the plumbing system and reduces pressure to one fixture or across the system, depending on the location. These leaks are most likely to occur at pipe joints, fixture connections, or supply lines that experience higher stress.

How old pipes affect water pressure

Homes with older plumbing systems may still have discontinued or degrading pipe materials, such as galvanized steel, cast iron, or clay. Depending on the material type, these pipes are at greater risk of structural damage, mold, clogs, and corrosion, which can affect water pressure and may require plumbing system repiping.

If cast iron and steel pipes accumulate scale buildup and rust, the passageways narrow, and blocked or clogged pipes reduce water flow. Pipes are also more likely to crack or collapse as they age and degrade, resulting in leaks that reduce water pressure.

Low water pressure in one fixture vs. the whole house

The range of low water pressure throughout your home may indicate the underlying cause. Low water pressure that’s restricted to one fixture is more often due to clogged aerators or faucets, kinked supply lines, or partially closed or faulty valves.

When multiple fixtures or the entire house experience low water pressure, the plumbing system likely has a single underlying problem rather than individual issues at each fixture. Your home’s main water valve may be partially closed or faulty, restricting supply to the entire system.

The pressure-regulating valve, which reduces incoming municipal water from the main valve to safe levels, can also fail, causing erratic pressure fluctuations. In some cases, low water pressure in the entire house is due to issues outside your system and with the municipal supply, such as planned maintenance shut-offs, high demand, or water main damage.

DIY Troubleshooting Tips

DIY troubleshooting helps determine whether low pressure stems from an easily fixed problem, such as a partially closed valve, or if there’s a more significant cause that requires professional attention. Try these DIY troubleshooting tips for low water pressure:

• Check the main shut-off valve: Locate your home’s main shut-off valve and ensure it’s fully open.

• Measure water meter readings: Turn off all water-using fixtures and appliances in your home, and take a reading of your water meter. Wait 30 minutes without using water, then check the meter again — an increased reading indicates a leak.

• Test the pressure-regulating valve: If you have a pressure gauge, attach it to an outdoor hose bib and turn the valve on to check that the plumbing water pressure is in the ideal range, about 50 to 60 PSI. If not, adjust the regulator by loosening the locking nut and turning the adjustment screw in quarter-turn increments.

• Check fixture valves: Ensure each fixture’s valves are fully open. If only your hot water pressure is low, check the shut-off valve on your water heater.

• Clean faucets and showerheads: Unscrew aerators from faucets and remove showerheads to clean buildup.

When to Call a Professional Plumber

If low water pressure persists despite troubleshooting, the underlying problem is probably more complex and requires the advanced knowledge and diagnostic methods of a professional. Call a professional plumber if you experience these signs:

• Sudden pressure drops without an obvious explanation
• High water bills
• Water damage, such as warped flooring, discolored walls, or bowing drywall
• Malfunctioning pressure regulator valve
• Faulty water shut-off valves
• Discolored water

How Oscar’s Plumbing & Rooter Can Help

At Oscar’s Plumbing & Rooter, our team of professional plumbers can help with low water pressure problems through systematic inspection and repair. We carefully inspect valves and connections for malfunctions, and we use water leak detection techniques and technology to identify leaks hidden behind walls or under floors. Using specialized cameras, we also inspect the inside of your pipes for breaks or obstructions.

Depending on our findings, we provide plumbing repair solutions such as:

• Descaling supply lines
• Fixing or replacing low water pressure faucets or showerheads
• Replacing shut-off valves
• Adjusting or replacing the pressure-regulating valve
• Repairing broken plumbing connections
• Replacing pipes