Start by finding where the pressure drops

Low water pressure usually comes from one of three places: the main water line into your house, the pipes inside your walls, or a single fixture like a shower head or faucet. The fastest way to narrow it down is to test the pressure at different points. Turn on a cold-water tap in your kitchen, then check a bathroom sink, then a shower. If all three are weak, the problem is likely at the meter or main line. If only one or two are weak, the issue is probably inside your house.

You can also check whether the problem is recent or has always been there. If pressure dropped suddenly, a pipe may have burst or a valve may have closed. If it has always been low, the issue might be distance from the water main, an undersized pipe, or a regulator set too low. Call your water company's customer service line to ask whether they have recorded any main breaks or pressure issues in your area — this takes two minutes and rules out problems you cannot fix yourself.

Key Takeaways

  • Test pressure at multiple fixtures to tell whether the problem is your main line, your house pipes, or a single faucet.
  • A closed shut-off valve under the sink or in the basement is the single most common cause and takes 30 seconds to fix.
  • Mineral buildup in aerators and shower heads can be cleared by soaking them in white vinegar for two to four hours.
  • If pressure is low everywhere and the main line is clear, you may need a pressure booster pump, which costs $300 to $800 installed.
  • Leaks in buried pipes are rare but expensive; a plumber can use a listening device to detect them without digging.

Check the shut-off valve and pressure regulator

Before you do anything else, look under the kitchen sink and in the basement or crawl space for the main shut-off valve — it is usually a ball valve or gate valve where the water line enters your house. Turn the handle to make sure it is fully open. A valve that is only partially open will cut pressure throughout the house. If the handle 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. This single step fixes the problem in roughly one out of every ten houses with low pressure.

Next, look for a pressure regulator — a small cylindrical device, usually brass or chrome, attached to the main water line near the shut-off valve. If you have one, it will have a screw or adjustment bolt on top. A regulator that is set too low will reduce pressure throughout your house. You can test the current pressure with an inexpensive pressure gauge (available at any hardware store for $10 to $20). Screw it onto an outdoor faucet or a washing machine outlet. Normal household pressure is 40 to 60 pounds per square inch (psi). If your gauge reads below 40 psi and the shut-off valve is fully open, the regulator may need adjustment. Turn the adjustment screw clockwise a quarter turn at a time, wait 30 seconds, and test again. Do not exceed 80 psi, which can damage appliances and pipes.

Clean aerators and shower heads

Mineral deposits from hard water build up inside the small screen at the tip of faucets and shower heads. This is the easiest problem to fix and costs nothing. Unscrew the aerator from the faucet or the shower head from the arm. Hold it up to the light — if you see white, tan, or rust-colored buildup, that is your culprit. Soak the part in white vinegar for two to four hours, then scrub the screen with an old toothbrush and rinse thoroughly. Screw it back on and test the pressure.

If the aerator is heavily clogged, soak it overnight or use a small needle or toothpick to clear the holes in the screen. For shower heads, you can also remove the screen entirely if it is removable, soak just the screen, and reassemble. This method works on kitchen faucets, bathroom sinks, outdoor spigots, and shower heads. If you have hard water (white buildup on faucets or soap scum that is hard to remove), cleaning aerators every six months will keep pressure steady.

Look for leaks in visible pipes

A leak in a pipe under your sink, in the basement, or in a crawl space will reduce pressure to fixtures downstream. Walk through your basement or crawl space with a flashlight and look for water dripping, pooling, or running down pipes. Check under sinks and around the water heater. Even a small pinhole leak will gradually lower pressure and waste water. If you find a leak in a visible pipe, you have two options: wrap it temporarily with plumber's tape or epoxy putty (a $5 fix that buys you time), or call a plumber to replace the section.

Leaks in buried pipes are harder to spot. Signs include soft spots in your yard, unusually green patches of grass, or a sudden spike in your water bill. If you suspect a buried leak, a plumber can use a listening device to locate it without digging. This service usually costs $100 to $300. Do not ignore a buried leak — it will only get worse and can undermine your foundation.

Replace undersized or corroded pipes

If pressure is low everywhere, the shut-off valve is open, the regulator is set correctly, and your water company confirms no main-line problems, the pipes inside your house may be too small or too old. Galvanized steel pipes, common in houses built before 1980, corrode from the inside over decades. The corrosion narrows the pipe opening and reduces flow. Copper and PVC pipes last much longer, but if your house has very old copper, pinhole leaks can develop.

Replacing all the pipes in a house is expensive — typically $3,000 to $8,000 depending on the size of the house and whether walls must be opened. Before you commit to this, ask a plumber to check the pipe diameter. Older houses sometimes have half-inch or three-quarter-inch main lines, which are undersized for modern water use. A plumber can tell you whether replacement is necessary or whether a pressure booster pump would solve the problem more cheaply.

Install a pressure booster pump if the main line is clear

If your water company confirms the main line has adequate pressure, but pressure is still low at your house, a pressure booster pump can increase flow. These pumps sit on the main water line and push water through your house at higher pressure. They are most useful in houses far from the water main, on hills, or in areas where municipal pressure is naturally low. A booster pump costs $300 to $800 installed, depending on the model and whether your plumber needs to modify your pipes.

Booster pumps come in two types: single-speed models that run constantly, and variable-speed models that turn on only when you open a tap. Variable-speed models are more efficient and quieter but cost more upfront. A plumber will install a check valve and pressure tank alongside the pump to prevent damage to your pipes and appliances. This is not a DIY job — installation requires cutting into the main line and ensuring proper backflow prevention.

Frequently Asked Questions

Why is pressure low in just one room?

Check the shut-off valve under that sink or in the wall — it may be partially closed. If the valve is open, the aerator or shower head probably has mineral buildup. Clean it with vinegar. If pressure is still low after cleaning, a plumber can check for a leak in the wall or a pinched pipe.

Can I increase pressure by adjusting the pressure regulator myself?

Yes, if you have a regulator. Buy a pressure gauge, test the current pressure, and turn the adjustment screw clockwise a quarter turn at a time. Wait 30 seconds between turns and retest. Never exceed 80 psi. If you are uncomfortable doing this, a plumber can adjust it for $75 to $150.

How do I know if I have a pressure regulator?

Look at the main water line where it enters your house, near the shut-off valve. A regulator is a small cylindrical device, usually brass or chrome, with a screw or bolt on top. Not all houses have one — if you do not see one, you do not have one.

What pressure should my house have?

Normal household water pressure is 40 to 60 psi. Anything below 40 psi will feel weak. Above 80 psi can damage pipes, water heaters, and washing machines. You can measure pressure with an inexpensive gauge from any hardware store.

Is low water pressure a sign of a serious problem?

Not always. Mineral buildup, a closed valve, or a regulator set too low are common and straightforward to fix. However, sudden pressure loss can mean a burst pipe or a leak. If pressure dropped overnight, call a plumber to check for leaks before the problem gets worse.