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

Low water pressure usually comes from one of three places: a problem at the meter or main line (which you cannot fix), a clogged aerator or showerhead (which takes two minutes), or sediment in your pipes or water heater (which you can sometimes clear). Start by checking whether the problem is everywhere in the house or just one fixture. If it is only one sink or shower, the fix is almost always the aerator or showerhead. If the whole house has low pressure, the cause is usually upstream — but before you call a plumber, you can rule out the simplest culprits yourself.

The good news is that most causes of low pressure are either free to fix or cost very little. A clogged aerator needs only a rinse. A partially closed shut-off valve needs only a quarter turn. Even flushing a water heater is a task most homeowners can do in an afternoon with basic tools. The only time you need a plumber is when the problem is inside the meter, in the main line, or in corroded pipes you cannot reach.

Key Takeaways

  • Low pressure in a single fixture usually means the aerator (the screen at the faucet tip) is clogged with sediment and can be cleaned in minutes by unscrewing it and rinsing it under running water.
  • If the whole house has low pressure, check the shut-off valve under the meter — it should be fully open, aligned with the pipe, and not partially closed.
  • Sediment buildup in your water heater can reduce pressure throughout the house, and flushing the tank once a year helps prevent this.
  • If pressure is low only on the hot water side, the problem is almost certainly inside the water heater or its supply lines, not the main line.
  • Call a plumber if the shut-off valve is fully open, aerators are clean, and pressure is still low — the problem is likely inside the meter or main line.

Clean the aerator or showerhead first

The aerator is the small screen at the tip of your faucet. It mixes air into the water stream and catches sediment. Over time, minerals and debris collect inside it and block the flow. This is the most common cause of low pressure in a single fixture, and it takes about two minutes to fix.

Unscrew the aerator by hand (turn it counterclockwise). If it is stuck, wrap a cloth around it for grip and use pliers — do not use excessive force. Once it is off, hold it under running water and rinse it thoroughly. Use an old toothbrush or soft brush to scrub away any white or brown buildup. If the screen is heavily clogged, soak it in white vinegar for 30 minutes, then scrub and rinse again. Screw it back on by hand until it is snug — do not overtighten.

For a showerhead, the process is identical. Unscrew it from the shower arm, rinse and brush the screen, and screw it back on. If you have a rainfall showerhead with multiple small holes, soak it longer in vinegar and use a toothpick to clear any holes that are still blocked. Most people find that cleaning a showerhead restores pressure noticeably within the same day.

Check the main shut-off valve

If low pressure affects the whole house, the next step is to find your main shut-off valve. It is usually located near the water meter, either inside the house (in a basement, crawlspace, or utility room) or outside (in a box in the yard or on the street side of your property). The valve looks like a handle or knob attached to a pipe. If you are not sure where it is, check your home inspection report or ask a neighbor — most houses on the same street have meters in the same location.

Make sure the valve is fully open. If it is a lever handle, it should be aligned with the pipe — parallel to it, not perpendicular. If it is a round knob, turn it counterclockwise until it stops. A partially closed valve is a common reason for low pressure throughout the house, and it is straightforward to close accidentally during repairs or maintenance. Some valves are stiff from age and may require a wrench to turn, but do not force it — if it will not budge, stop and call a plumber rather than risk breaking it.

If the valve was partially closed, opening it fully should restore pressure within seconds. If pressure is still low and the valve is fully open, the problem is either inside the meter (which you cannot access) or in the main line before it reaches your house — both require a call to your water utility or a plumber.

Flush your water heater if hot water pressure is low

If low pressure affects only the hot water side, the problem is in your water heater or its supply lines. Over time, sediment settles at the bottom of the tank and can block the outlet pipe, reducing flow. Flushing the tank once a year prevents this and extends the life of the heater. The process is straightforward and takes about 45 minutes from start to finish.

Turn off the power to the heater (switch off the breaker for electric, or set the gas valve to pilot for gas). Turn off the cold water inlet valve at the top of the tank. Attach a garden hose to the drain valve at the bottom of the tank and run it to a floor drain or outside. Open the drain valve and let the tank empty — this takes 20 to 30 minutes. Close the drain valve, turn the cold water inlet back on, and let the tank refill. Turn the power back on and wait 30 minutes before using hot water.

If you are not comfortable doing this yourself, a plumber can flush the tank in about an hour. If flushing does not restore pressure, the problem may be a failing dip tube (the pipe inside the tank that carries cold water down) or sediment in the hot water supply line, both of which require professional repair.

Look for leaks or damage in visible pipes

Walk through your basement, crawlspace, or any area where you can see water pipes. Look for small drips, wet spots on the floor, or corrosion on the pipes themselves. A slow leak upstream of your fixtures will reduce pressure throughout the house, even if you do not see water pooling. Pay special attention to joints and connections, where leaks are most common.

Corrosion appears as white, blue, or green deposits on copper pipes, or as rust-colored staining on steel pipes. If you see corrosion, the pipe may be corroded on the inside as well, which restricts water flow. This is a sign that the pipes are aging and may fail soon. Take a photo and show it to a plumber — they can advise whether the pipes need replacement or whether the corrosion is only surface-level and not affecting flow.

When to call a plumber

Call a plumber if you have cleaned aerators, opened the main shut-off valve fully, flushed the water heater (if low pressure is on the hot side only), and pressure is still low. The problem is likely inside the meter, in the main line before it reaches your house, or in corroded pipes inside your walls — none of which you can fix yourself. A plumber will have the tools and knowledge to diagnose the exact cause.

A plumber will use a pressure gauge to measure the water pressure at the meter. If pressure is low there, the problem is with the utility or the main line, and the utility company is responsible for fixing it. If pressure is normal at the meter but low inside the house, the plumber will know the problem is in your supply lines or fixtures, and can locate and repair it. This test usually takes 15 to 20 minutes and costs between $75 and $150, depending on your area.

Frequently Asked Questions

Can I increase water pressure by adjusting something at the meter?

The shut-off valve at the meter is the only thing you should touch, and only to make sure it is fully open. Do not adjust the pressure regulator (a bell-shaped device near the meter) — that requires a plumber and a pressure gauge. Adjusting it incorrectly can damage pipes or fixtures.

Will cleaning aerators really make a difference?

Yes, if low pressure is in one fixture only. A clogged aerator can reduce flow by 50 percent or more. It is the first thing to check and takes two minutes, so it is always worth trying before calling anyone.

How often should I flush my water heater?

Once a year is standard maintenance. If you have hard water (lots of minerals), flush it twice a year. Flushing removes sediment that reduces pressure and efficiency, and it extends the life of the tank by several years.

What if pressure is low only in the morning?

This usually means sediment has settled overnight and is blocking the outlet of the water heater. Run hot water for a minute or two to stir it up, and pressure should return to normal. If it happens every morning, flush the water heater soon.

Does low water pressure mean I need new pipes?

Not always. Start with the straightforward fixes — clean aerators, open the shut-off valve, flush the heater. If pressure is still low after that, a plumber can test the pressure at the meter and tell you whether the problem is in your pipes or upstream. Corroded pipes do need replacement eventually, but that is a decision to make with a plumber after they have diagnosed the problem.