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

Low water pressure usually comes from one of three places: a problem at your meter or main shutoff valve, a clogged aerator or showerhead, or mineral buildup in your pipes. The first two you can often fix in minutes. The third requires a plumber. Before you call one, check whether the problem is everywhere in your house or only in one fixture — that tells you which direction to look.

Start by turning on a faucet in your kitchen and one in your bathroom at the same time. If both run weak, the problem is in your main line. If only one runs weak, the problem is in that fixture or the line feeding it. This one observation saves you hours of troubleshooting.

Key Takeaways

  • Low pressure everywhere in the house usually means a problem at your meter, main shutoff valve, or pressure regulator — call your water company first to rule out their side.
  • Low pressure in one fixture usually means a clogged aerator or showerhead, which you can clean by unscrewing it and rinsing it under hot water.
  • If your pressure regulator is set too low, you can adjust it yourself with a wrench, but check your local code first — some areas have rules about how high you can set it.
  • Mineral buildup in pipes requires a plumber and usually costs between $300 and $1,000 depending on how much of your system is affected.
  • Never ignore a sudden drop in pressure — it can mean a leak in your main line, which wastes water and can damage your foundation.

Clean the aerator or showerhead first

An aerator is the small screen at the tip of your faucet. Mineral deposits clog it over time, especially in areas with hard water. Unscrew it by hand — most turn counterclockwise — and hold it under hot running water. Use an old toothbrush to scrub the screen and the inside of the aerator itself.

If scrubbing does not work, soak the aerator in white vinegar for two to four hours, then scrub again. Rinse it thoroughly and screw it back on. Do the same for showerheads. This takes ten minutes and costs nothing. If pressure returns to normal, you are done.

If you have low pressure only in your shower, also check whether the shutoff valve behind the showerhead is fully open. Some shower valves have a small knob or lever that can be partially closed without you noticing. Turn it all the way to the open position.

Check your main shutoff valve and meter

If pressure is low everywhere, look at the shutoff valve where the water line enters your house. This is usually in your basement, crawlspace, or under the kitchen sink. The valve should be fully open — if it is a lever, it should point in the same direction as the pipe; if it is a round knob, turn it counterclockwise until it stops.

Next, look at your water meter, which is usually near the shutoff valve or outside your house in a box in the ground. If the meter is spinning even though no water is running, you have a leak in your main line. Call a plumber when ready — a leak in the main line wastes water and can damage your foundation.

If the shutoff valve is fully open and there is no leak, call your water company. Low pressure on their side of the meter is their problem to fix, and they will not charge you. They can tell you in one call whether the issue is at the meter or in the street.

Adjust your pressure regulator if you have one

Many homes have a pressure regulator — a bell-shaped device on the main water line near the shutoff valve. It keeps pressure from getting too high and damaging your pipes. If it is set too low, your pressure will be weak everywhere.

Look for a screw or bolt on top of the regulator. Turn it clockwise with a wrench to increase pressure, but only a quarter turn at a time. Check the pressure at a faucet after each adjustment. Stop when pressure feels normal. Do not turn it more than one full rotation — you risk damaging the regulator or exceeding your local code.

Before you adjust it, check your local plumbing code or call your water company. Some areas have rules about how high residential pressure can go — usually between 60 and 80 pounds per square inch. If you are not sure, have a plumber adjust it for you. A service call usually costs $100 to $200.

Understand mineral buildup and when to call a plumber

If your home is more than 20 years old and you have hard water, mineral deposits can build up inside your pipes over decades. This narrows the pipes and reduces flow. You cannot fix this yourself — a plumber has to either flush the system with a chemical solution or replace the affected pipes.

Signs of mineral buildup include low pressure that gets worse over months or years, discolored water, or low pressure that started after you had other plumbing work done. A plumber can diagnose this by checking pressure at different points in your system. The cost depends on how much of your system is affected — usually $300 to $1,000.

If you have hard water, a water softener can slow down future buildup, but it will not fix existing deposits. A water softener costs $500 to $2,500 installed and requires ongoing maintenance.

Know when low pressure is a sign of a bigger problem

A sudden drop in pressure — not gradual over months, but noticeable in a day or two — often means a leak in your main line. Check your water meter: if it is spinning when no water is running, you have a leak. Call a plumber the same day. A leak in the main line can waste thousands of gallons a month and damage your foundation.

Low pressure after you had plumbing work done usually means air in the lines. Run all your cold-water faucets for a few minutes to push the air out. If pressure does not return to normal, call the plumber who did the work — they may have left a valve partially closed.

What to expect from a plumber visit

If you need a plumber, they will start by checking pressure at different points in your system to find where the problem is. They will look at your regulator, check for leaks, and inspect visible pipes. A diagnostic visit usually takes 30 to 60 minutes and costs $100 to $200.

If they find mineral buildup, they will quote you for flushing or pipe replacement. If they find a leak, they will tell you where it is and what it costs to fix. Get a second opinion if the quote is more than $1,000 — plumbing prices vary widely by region and by contractor.

Frequently Asked Questions

Can low water pressure damage my appliances?

Yes. Dishwashers and washing machines need a minimum pressure to work properly — usually 20 pounds per square inch. If your pressure is below that, they may not fill completely or may run very slowly. Check your appliance manual for the minimum pressure it needs.

Will a water softener fix low pressure?

No. A water softener prevents future mineral buildup but does not remove deposits already in your pipes. If low pressure is caused by existing mineral buildup, you need a plumber to flush the system or replace pipes. A water softener is a preventive step, not a cure.

How do I know if my pressure regulator is broken?

A broken regulator usually causes pressure that is either very high or very low and does not respond to adjustment. If you turn the screw and nothing changes, or if pressure suddenly spikes, the regulator may be stuck or failed. Have a plumber replace it — a new one costs $200 to $400 installed.

Is low pressure in just the hot water normal?

No. If cold water pressure is normal but hot water pressure is weak, the problem is usually in your water heater or the line feeding it. Check whether the shutoff valve on the hot-water line is fully open. If it is, the water heater may have mineral buildup inside, and a plumber can flush it.

What is normal water pressure for a house?

Normal residential pressure is between 40 and 80 pounds per square inch. Most people notice weak pressure below 40 psi. If you want to know your exact pressure, a plumber can measure it with a gauge for $50 to $100, or you can buy a pressure gauge yourself for $10 to $20 and check it.