Start with the water meter shut-off valve

Low water pressure often comes from a partially closed valve that you can open yourself in minutes. The main shut-off valve sits where the water line enters your house—usually in the basement, crawl space, or under the kitchen sink. It looks like a brass or chrome ball valve (shaped like a lever) or a gate valve (shaped like a wheel). If the lever is perpendicular to the pipe, it is closed or partially closed. Turn it so the lever runs parallel to the pipe.

After you open it, turn on a faucet and wait 30 seconds to see if pressure improves. This is the fastest fix because it costs nothing and solves the problem in many homes where someone accidentally closed the valve during a repair or emergency.

Key Takeaways

  • Check your main shut-off valve first—a partially closed valve is the most common cause of low pressure and takes seconds to fix.
  • Sediment buildup in aerators and screens happens gradually and can be cleaned by unscrewing the fixture head and rinsing the parts.
  • A faulty pressure regulator (a bell-shaped device near the main shut-off) can be tested by a plumber and replaced for $150 to $300.
  • If only one fixture has low pressure, the problem is local to that fixture; if the whole house is affected, the problem is in the main line or regulator.
  • Mineral deposits in old pipes cannot be cleared without replacing the pipes, which is a job for a licensed plumber.

Clean the aerator screens on individual faucets

Sediment and mineral deposits collect in the aerator—the small screen at the tip of your faucet—and restrict flow over time. Unscrew the aerator by hand (turn counterclockwise) or use a wrench if it is stuck. Rinse it under running water and use an old toothbrush to scrub away any white or brown buildup.

If the aerator is heavily clogged, soak it in white vinegar for 30 minutes, then scrub again. Screw it back on and test the pressure. This fix works on kitchen and bathroom faucets and takes about five minutes per fixture. If pressure is still low after cleaning, the problem is upstream—in the supply line or regulator, not the faucet itself.

Check for leaks in your supply lines

A hidden leak in your water supply pipes reduces pressure throughout the house because water is escaping before it reaches your fixtures. Look under sinks, in the basement, and along exterior walls for wet spots, stains, or the sound of running water when no faucet is on. Check your water meter: if the dial is moving when all fixtures are off, you have a leak.

Small leaks at connection points (where pipes join) can sometimes be tightened with a wrench, but leaks inside walls or underground require a plumber to locate and repair. Do not ignore a leak—it wastes water and can damage your home's structure. Call a plumber if you suspect a leak you cannot see or reach.

Test and replace the pressure regulator

The pressure regulator is a bell-shaped or cylindrical device mounted on the main water line just after the shut-off valve. It keeps incoming pressure from the street at a safe level for your home's pipes (usually 40 to 60 pounds per square inch). If the regulator fails, pressure can drop suddenly or fluctuate wildly.

You can test pressure with an inexpensive gauge (available at hardware stores for $10 to $20). Screw the gauge onto an outdoor faucet or a hose bib and turn the valve on. A reading below 40 psi suggests a failed regulator. A plumber can replace a regulator for $150 to $300 in labor and parts. This is not a DIY repair—regulators require proper tools and knowledge to install safely.

Identify whether the problem is whole-house or one fixture

Turn on every faucet in your home at once—kitchen, bathrooms, outdoor spigots, showers. If pressure drops everywhere, the problem is in your main line or regulator. If pressure is normal everywhere except one or two fixtures, the problem is local to those fixtures (usually a clogged aerator or a failing valve inside the fixture).

This distinction saves time because it tells you whether to call a plumber or straightforward clean an aerator. Local problems are almost always fixable by cleaning or replacing the fixture itself. Whole-house problems usually require professional diagnosis because they involve the main supply line or regulator.

Understand when mineral buildup requires pipe replacement

In homes with very old galvanized steel pipes or in areas with extremely hard water, mineral deposits can accumulate inside the pipes themselves over decades. This buildup narrows the pipe opening and reduces pressure gradually. Unlike aerator screens, you cannot clean deposits inside the pipes without replacing them.

If your home was built before 1970 and has always had low pressure that worsens over time, galvanized pipe corrosion is likely. Replacing old pipes is a significant project that requires a licensed plumber and can cost several thousand dollars depending on how much of your system needs replacement. A plumber can inspect a section of pipe to confirm the problem before you commit to a full replacement.

Know when to call a plumber

Call a plumber if pressure remains low after you have opened the main shut-off valve and cleaned aerators, if you suspect a leak you cannot locate, if the pressure regulator needs testing or replacement, or if pressure drops suddenly without an obvious cause. A plumber has tools to measure pressure, locate leaks, and diagnose problems in the main line that you cannot see.

Most plumbers charge a service call fee ($75 to $150) to diagnose the problem, and that fee is usually credited toward repair costs if you hire them to fix it. Getting a diagnosis is worth the cost because it tells you whether the fix is straightforward (a few dollars and 30 minutes) or complex (pipe replacement or regulator work).

Frequently Asked Questions

Why did my water pressure drop suddenly?

Sudden pressure loss usually means a valve was accidentally closed, a regulator failed, or a leak developed in a visible supply line. Check the main shut-off valve first, then look for leaks under sinks and in the basement. If you find neither, the regulator or an underground line may have failed—call a plumber to diagnose.

Can I increase water pressure beyond what the regulator allows?

The regulator is set to protect your pipes from damage caused by excessive pressure. Adjusting it yourself can harm fixtures and cause leaks. If you want higher pressure, a plumber can adjust the regulator safely, but pressures above 80 psi risk damaging your home's plumbing system.

Will cleaning aerators fix low pressure in my shower?

Cleaning the aerator on a showerhead works the same way as on a faucet. Unscrew the showerhead, rinse it, and scrub away mineral buildup. If pressure is still low after cleaning, the problem is in the supply line to that shower or in the whole house, not the showerhead itself.

How do I know if my pressure regulator is broken?

A broken regulator usually causes pressure to drop below 40 psi or to fluctuate wildly between high and low. You can test this with an inexpensive pressure gauge on an outdoor faucet. If the reading is consistently low and the main valve is open, the regulator is likely the problem and needs replacement by a plumber.

Is low water pressure a sign of a serious plumbing problem?

Low pressure is usually fixable and not an emergency, but it can signal a leak or failing component that will worsen over time. A sudden drop in pressure warrants a plumber's inspection because leaks waste water and can damage your home. Gradual pressure loss over years is often mineral buildup and less urgent.