Start with the pressure regulator and main shutoff valve

Low water pressure usually comes from one of three places: your municipal supply, a clogged pipe, or a pressure regulator that is set too low. The fastest fix is to check your pressure regulator, a brass or plastic valve typically mounted on the main water line where it enters your home, often in the basement or under the kitchen sink.

The regulator has a screw on top or a bolt you can adjust with a wrench. Turn it clockwise to increase pressure. Most homes are set between 40 and 60 pounds per square inch (PSI). If you do not have a pressure gauge, you can buy one at any hardware store for under $15—screw it onto an outdoor faucet to read your current pressure. Increase the regulator slowly, a quarter turn at a time, and check the gauge after each adjustment. Do not exceed 80 PSI, as that can damage pipes and appliances.

If you do not have a regulator, or if adjusting it does not help, the problem lies elsewhere in your system.

Key Takeaways

  • A pressure regulator set too low is the most common cause of weak water pressure and can usually be adjusted with a wrench in minutes.
  • Water pressure should stay between 40 and 80 PSI; you can measure yours with a $15 gauge screwed onto any outdoor faucet.
  • Mineral buildup in aerators and showerheads is the second most common cause and is fixed by soaking the part in vinegar overnight.
  • If only one faucet has low pressure, the problem is local to that fixture; if the whole house is affected, the issue is in your main line or regulator.
  • Pinhole leaks, corroded pipes, and undersized water lines require a plumber to diagnose and repair.

Clean aerators and showerheads first

Before you adjust anything, check whether the low pressure is coming from one faucet or the whole house. Turn on the kitchen sink, a bathroom sink, and a shower. If only one or two are weak, the problem is usually mineral buildup in the aerator—the small screen at the tip of the faucet.

Unscrew the aerator by hand or with a wrench, depending on how tight it is. Soak it in white vinegar for at least four hours, or overnight if the buildup is heavy. Use an old toothbrush to scrub away the mineral deposits, then rinse it under running water and screw it back on. Do the same for showerheads: unscrew them, soak in vinegar, scrub, and reinstall.

This fix solves the problem in roughly half of all low-pressure complaints. If pressure is still weak after cleaning, move on to checking the main shutoff valve.

Check and adjust the main shutoff valve

The main shutoff valve controls water flow into your entire home. It is usually located near the water meter, in the basement, or outside in a box at the street. The valve handle should be parallel to the pipe when it is fully open. If it is at an angle, someone may have partially closed it.

Turn the handle so it is parallel to the pipe. If the valve is stiff, do not force it—explore penetrating oil (like WD-40) and wait 15 minutes before trying again. Once it is fully open, check your pressure again. A partially closed main valve is the second most common cause of whole-house low pressure.

If the valve is already open and pressure is still low, you may have a leak in the main line, corrosion inside the pipes, or an undersized water line. These require a plumber to diagnose.

Look for leaks in visible pipes

A leak anywhere in your main water line will reduce pressure throughout the house. Walk through your basement or crawlspace and look for water dripping, pooling, or staining on pipes. Pay special attention to joints and bends, where leaks are most common.

If you find a small drip, you can temporarily wrap the leak with plumber's tape or a rubber patch kit from the hardware store. However, a leaking main line should be repaired by a plumber, as the patch is temporary and the leak will worsen. If you do not see any visible leaks but pressure is still low everywhere, the leak may be underground or inside a wall.

Understand when to call a plumber

Call a plumber if adjusting the regulator, cleaning aerators, and opening the main shutoff valve do not restore pressure. You will also need a plumber if you suspect a leak in the main line, if pressure is low only on the hot water side (which suggests a problem with the water heater), or if pressure drops suddenly after being normal for years.

A plumber can use a pressure gauge to pinpoint where the problem is, check for pinhole leaks in copper pipes, and test whether your water line is undersized for your home's demand. Undersized lines are common in older homes and require replacing the main line—a bigger job, but one that permanently fixes the problem.

If your water comes from a well rather than a municipal supply, low pressure usually means the pump is failing or the pressure tank needs adjustment. A well service company can diagnose and repair this.

Pressure tanks and well systems

Homes with well water use a pressure tank to store water and maintain consistent pressure. The tank has an air valve on top. If pressure drops suddenly, the tank may have lost its air charge. You can check this by tapping the tank—the top half should sound hollow (air) and the bottom half should sound full (water).

If the tank sounds full all the way up, it has lost its air charge and needs to be re-pressurized. You can do this yourself with an air compressor and a tire valve, but it is easier to call a well service company. They will also check the pump and pressure switch, both of which can fail and cause low pressure.

Frequently Asked Questions

Is low water pressure a sign of a serious problem?

Not always. A clogged aerator or a regulator set too low is harmless and straightforward to fix. However, sudden pressure loss or pressure that drops only on the hot side can indicate a failing water heater or a leak in the main line. If pressure changes suddenly, have a plumber check it.

Can I increase pressure above 80 PSI?

You can, but you should not. Pressure above 80 PSI can crack pipes, damage water heater seals, and shorten the life of appliances like washing machines and dishwashers. If you need more pressure than 80 PSI, the problem is usually a leak or an undersized line, not the regulator setting.

Why is only my hot water pressure low?

This usually means the problem is in your water heater, not the main line. The heater's dip tube or internal parts may be corroded, or the heater may be failing. Have a plumber inspect the heater. Do not adjust the regulator—that will not help.

How much does it cost to have a plumber check water pressure?

A diagnostic visit typically costs between $100 and $200, depending on your area and the plumber. If the plumber finds the problem and you hire them to fix it, that fee is usually applied to the repair cost.

What if my pressure regulator is broken?

A broken regulator needs to be replaced. The part itself costs $50 to $150, and installation takes about an hour. A plumber can replace it, or a handy homeowner can do it with a wrench and some plumber's tape on the threads. Turn off the main water, unscrew the old regulator, and screw in the new one.