Where low pressure comes from, and what you can fix yourself

Low water pressure usually starts at one of three points: the main shutoff valve, the water meter, or the pressure regulator. If your whole house has weak pressure, the problem is almost always one of these three, and you can check all of them without calling a plumber. If only one room or fixture has low pressure, the issue is downstream—in that room's supply line or the fixture itself—and the fixes are different.

Start by confirming whether the problem is yours or your water company's. Call your neighbors or check your town's water department website; if they are reporting outages or main breaks, wait. If pressure is low only in your house, move to the main shutoff valve.

Key Takeaways

  • The main shutoff valve, water meter valve, and pressure regulator are the three most common causes of low pressure in the whole house, and you can inspect all three yourself.
  • A partially closed shutoff valve looks like a lever or a round knob; a lever should point along the pipe, and a knob should turn freely—if either is stuck or angled wrong, that is your problem.
  • If pressure is low in only one room or at one fixture, the issue is in that room's supply line or the fixture itself, not in your main system.
  • A pressure regulator that is set too low can be adjusted upward, but if it is broken, it must be replaced by a plumber.
  • Sediment buildup in aerators and screens is the most common cause of low pressure at a single faucet and takes five minutes to clean.

Check and adjust the main shutoff valve

The main shutoff valve is usually near the water meter, either inside your house (in a basement, crawl space, or utility closet) or outside (in a box in the ground or on the street-facing wall). It controls all water entering your home. If it is partially closed, pressure everywhere will drop.

Look at the valve. If it has a lever handle, it should point along the direction of the pipe—that means it is fully open. If the lever is angled across the pipe or perpendicular to it, turn it to align with the pipe. If it has a round knob, turn it counterclockwise until it stops; do not force it. Once it is fully open, check your pressure. If it has improved, you are done.

If the valve is already fully open and you cannot turn it further, or if it is stuck in one position, do not force it. A stuck valve may be corroded inside and forcing it can break it. Call a plumber to replace it.

Inspect the water meter valve

Just before or after your water meter (depending on your setup), there is often a second valve. This one is smaller and is sometimes overlooked. Check it the same way: a lever should point along the pipe, and a knob should turn freely counterclockwise. If it is partially closed, open it fully.

If you cannot locate a second valve, your meter may not have one—that is normal. If you do find one and it is stuck, do not force it. Call your water company or a plumber; in some places, the meter valve is owned by the utility and they must handle it.

Test and adjust the pressure regulator

A pressure regulator is a bell-shaped or cylindrical device on the main water line, usually near the shutoff valve. It keeps pressure from getting too high and damaging pipes and fixtures. If it is set too low, your whole house will have weak pressure.

Look for a screw or adjustment bolt on top of the regulator. If you see one, you can try raising the pressure. Use an adjustable wrench to turn the bolt clockwise a quarter turn, then test your pressure. If it has improved, you are done. If not, turn it another quarter turn and test again. Do not turn it more than one full rotation; regulators have limits, and exceeding them can damage the device.

If there is no adjustment screw, or if you have turned it fully and pressure is still low, the regulator is broken and must be replaced. This is a job for a plumber—regulators are under pressure and require soldering or professional fittings to install safely.

Clean aerators and screens at individual faucets

If pressure is low at only one faucet or showerhead, sediment or mineral buildup in the aerator (the screen at the faucet tip) is usually the cause. This is the easiest fix and takes five minutes.

Unscrew the aerator by hand or with a wrench, depending on how tight it is. Rinse it under running water and use an old toothbrush to scrub away any white or brown deposits. If deposits are heavy, soak the aerator in white vinegar for an hour, then scrub again. Screw it back on and test. If pressure returns to normal, you are done.

For a showerhead, the same method works: unscrew it, clean the screen, and reinstall. If you cannot unscrew it by hand, wrap a cloth around it and use a wrench to avoid scratching the finish.

Clear sediment from supply lines in one room

If all fixtures in one room have low pressure but other rooms are fine, sediment may be trapped in that room's supply line. This is less common but happens after water main work in your area or if your water heater is old.

Turn off the water at the main shutoff valve. Open the lowest faucet in the affected room (usually a basement sink or outdoor spigot) and let water drain for a few minutes. Close that faucet, then turn the main valve back on. Run water in the affected room for a minute or two. This flushes loose sediment out. If pressure improves, you are done. If not, the line may need professional flushing or replacement.

When to call a plumber

Call a plumber if the main shutoff valve is stuck or broken, if the pressure regulator has no adjustment screw or cannot be adjusted high enough, if you have cleaned aerators and flushed lines and pressure is still low, or if low pressure appeared suddenly after you heard a loud bang or saw water leaking from the meter or main line.

A plumber can test your water pressure with a gauge (normal household pressure is 40 to 80 pounds per square inch), identify which part is failing, and replace it. They can also check for leaks in hidden supply lines, which can reduce pressure throughout the house.

Frequently Asked Questions

Is low water pressure dangerous?

Low pressure itself is not dangerous, but it can be a sign of a leak in your main line or meter. If pressure dropped suddenly or you see wet spots in your yard or basement, call a plumber to check for leaks. Slow leaks waste water and can damage your foundation over time.

Can I increase pressure above 80 PSI?

You should not. Household plumbing is designed for 40 to 80 PSI. Pressure above 80 PSI can damage pipes, water heaters, and fixtures, and may void warranties. If your regulator is set to 80 and pressure is still low, the problem is elsewhere, not with the regulator setting.

Why is pressure low only in the morning?

Morning low pressure is often caused by air in the lines after the water company does maintenance overnight. Run a cold-water faucet for a minute or two to push the air out. If pressure does not return to normal after a few hours, call your water company to ask if they worked on the main.

Will a water pressure booster pump help?

A booster pump can increase pressure if your main line pressure is genuinely low (below 40 PSI) and you have ruled out the shutoff valve, meter valve, and regulator. However, a pump is expensive and requires professional installation. Fix the three common causes first; most low-pressure problems are solved by opening a stuck valve or cleaning an aerator.

What if pressure is high, not low?

High pressure (above 80 PSI) is the opposite problem and is usually caused by a faulty pressure regulator. A regulator that is broken or set too high can damage pipes and fixtures. Call a plumber to test your pressure and replace the regulator if needed.