How to Fix Low Water Pressure

Quick answer: where to start

Low water pressure usually comes from one of a few things: a partly closed valve, a clogged aerator or showerhead, a hidden leak, a worn pressure regulator, pipes narrowed by buildup or corrosion, or a problem with the water supply itself. The fastest way to sort them out is to work in this order:

Measure the pressure with a gauge.
Check whether the problem is at one fixture or the whole house.
Rule out the simple causes (valves, aerators, hoses).
Check for leaks and ask whether neighbors have the same problem.
Call a plumber if the cause is not obvious or involves the regulator, buried pipe or a well system.

Is your pressure actually low?

A shower that feels weak is not always low pressure. Clogged fixtures, a flow-restricting showerhead (see low-flow shower heads and flow rates), or demand from other fixtures can all make water feel weak. A pressure gauge takes the guesswork out.

A basic gauge screws onto an outdoor hose bib or a laundry sink connection and usually costs about the price of a few coffees at a hardware store. To use it:

Turn off water-using appliances and fixtures in the house so nothing is drawing water.
Screw the gauge onto the hose connection.
Open the tap fully and read the dial.

Most plumbing codes set 80 psi as the maximum static pressure for a home, and 40 to 60 psi is commonly cited as typical. Local code can differ, so treat these as rough guides.

Is 40 psi too low?

A reading of 40 psi is at the low end of the range most sources call normal. Many homes work fine at that pressure, but you may notice weak flow in showers, on upper floors, or when two fixtures run at once. If you are seeing real problems at 40 psi, a plumber can tell you whether the regulator can safely be set higher. Readings well below 40 psi, or readings that swing up and down, deserve a closer look.

It also helps to check the gauge when no water is running and again while a tap runs. A big drop while water flows can point to a restriction in the supply line.

One fixture or the whole house?

This single question narrows things down quickly.

One faucet or showerhead is weak: the cause is almost always at that fixture, such as a clogged aerator, a clogged showerhead, or a partly closed shut-off valve under the sink.
Only hot water is weak: look at the water heater side, including its shut-off valve and any sediment buildup.
Every fixture is weak: the cause is likely upstream, such as the main shut-off valve, the meter valve, the pressure regulator, a leak, supply piping, or the water supply itself.
Weak at upper floors only: elevation naturally lowers pressure, and a restriction in the supply makes this more noticeable.

Fixes for a single faucet or shower

Clean the faucet aerator

The aerator is the small screen at the tip of most faucets. Sediment and mineral scale collect there and restrict flow.

Unscrew the aerator by hand. If it is stuck, wrap the faucet end in a cloth before using pliers so you do not mar the finish.
Rinse out loose debris.
Soak the parts in white vinegar for a few hours or overnight to loosen scale, then scrub gently with an old toothbrush.
Reinstall and test. Replace the aerator if it is damaged or still clogged.

Clean the showerhead

Twist the showerhead off the arm, rinse the internal screen and check the nozzles for scale. Soaking in vinegar is a common approach, but avoid it on finishes the manufacturer says are not vinegar safe (some brass, nickel or coated finishes can be marked). If your shower has a visible white crust, see our guide on whether your shower water is hard water.

Check under-sink shut-off valves

Valves under sinks and behind toilets can be partly closed, especially after plumbing work. Turn the handle fully open. If a valve is stiff, leaking or corroded, do not force it; a plumber can replace it.

Look for kinked supply hoses

Flexible supply lines to washing machines, dishwashers and ice makers can kink behind appliances. Straighten any bends and check that the fittings are not clogged with debris.

Fixes for the whole house

Check the main shut-off valve

Find your main shut-off valve (often in a basement, utility room, garage or near the water heater) and confirm it is fully open. Gate valves can feel loose or may not fully open even when the handle looks open. A ball valve has a lever that should run parallel to the pipe when open. If the valve is old, stiff or leaking, avoid forcing it.

Check the meter valve

Between the street and your house there is typically a meter with a valve controlled by the water utility. In many areas this is the utility’s equipment, so call them rather than adjusting it yourself.

Call the water company or ask neighbors

If pressure dropped suddenly, check with neighbors or the utility. Main breaks, repairs, hydrant use, or peak demand can lower pressure for a short time. If the problem is general and temporary, the utility can often confirm.

Test for a hidden leak

A leak can reduce the water that reaches your fixtures. A common test is:

Turn off every tap and water-using appliance in the house.
Read the water meter (many have a small leak indicator dial or triangle).
Wait about two hours without using water, then read it again.

If the meter moved, water is going somewhere. Also look for wet spots on walls or ceilings, a damp basement or crawl space, unexplained increases in your water bill, or a sound of running water when nothing is on. A leaking supply line is a job for a plumber or leak-detection professional, especially if it is buried or inside a wall. See signs of a leaking pipe and, for the buried line, what to do about a leaking water main.

Pressure regulator problems

Many homes on municipal water have a pressure-reducing valve (PRV), often a bell-shaped brass fitting near where the main line enters the house. It lowers incoming street pressure to a safer household level. If it fails, you can end up with low pressure, high pressure, or pressure that swings.

Have a plumber adjust or replace the regulator rather than adjusting it yourself. Raising the pressure can stress the water heater, its temperature and pressure (T&P) relief valve and supply hoses, and 80 psi is the usual plumbing-code maximum.

If the regulator is old, noisy, leaking, or drifting, it may need replacing. That is a plumber’s job because it involves the main supply line.
Keep the gauge on a hose bib to check the result after the plumber’s work.

High pressure can damage fixtures, hoses and water heaters, so do not “fix” low pressure by raising the regulator setting.

Corroded or clogged pipes

Older homes with galvanized steel supply lines can develop rust and mineral buildup inside the pipe, which narrows the passage over time. Signs include low pressure throughout the house, rusty or discolored water, and flow that gets weaker year after year. Our guides on light brown water from the faucet and yellow shower water cover the discoloration side.

Descaling or cleaning inside supply pipes generally is not a DIY job. In many cases the longer-term fix is replacing the affected section or the whole supply line with modern piping (see replumbing a house and copper vs plastic water pipe). A plumber can inspect, tell you what material you have, and quote the work.

Low pressure on well water

If you are on a private well, pressure comes from a pump and a pressure tank rather than a city main, so a sudden drop has different causes. Possibilities include a failing pump, a pressure switch problem, a waterlogged or failed pressure tank, a clogged sediment filter, a lowered water level in the well, or a power issue.

A few safe checks:

Replace or clean the whole-house sediment filter if you have one and it is dirty.
Check whether the circuit breaker for the well pump has tripped.
Notice whether the pump cycles on and off rapidly, which is a sign of a pressure tank problem.

Well pumps and pressure tanks involve electrical power and stored pressure. Do not open the pressure switch or work on live wiring yourself. Call a licensed well or pump contractor or an electrician if the pump will not run, the breaker keeps tripping, or the system cycles rapidly.

How much does it cost to fix?

Costs vary widely by region and by cause, so any single figure is unreliable. In general:

Cleaning an aerator or showerhead costs very little.
A pressure gauge is a small purchase.
Replacing a regulator, a shut-off valve or a section of pipe is plumber work and costs more.
Whole-house repiping, well pump replacement, and finding and repairing a buried leak are among the more expensive outcomes.

The best way to get a realistic number is to ask two or three licensed plumbers for written quotes after they diagnose the cause.

When to call a plumber

Call a licensed plumber (or the water utility, where noted) if:

The cause is not found after the simple checks above.
You suspect a leak inside walls, under a slab or underground.
The pressure regulator needs replacing or keeps drifting.
Pipes are corroded, or you have galvanized supply lines with declining flow.
Pressure changes dramatically from hour to hour.
Toilets back up or drains behave oddly along with the pressure problem.
You are on a well and the pump, switch or tank seems to be involved.
You see signs of water damage, such as stains, mold, warped floors or a musty smell.

If you find water actively flowing from a pipe, shut off the main valve and call a plumber right away.

FAQ

How can I increase my low water pressure?

Start with the free fixes: open all valves fully, clean aerators and showerheads, and straighten hoses. Then measure with a gauge. If the whole house is weak, check for leaks and the pressure regulator, and call a plumber if you cannot find the cause.

Why is my water pressure low all of a sudden on well water?

Sudden drops on a well point to the pump, pressure switch, pressure tank, a clogged filter, a tripped breaker, or a falling water level. Check the filter and breaker, then call a well professional rather than opening electrical components yourself.

Can a water softener or hard water cause low pressure?

Mineral scale can clog aerators, showerheads and, over many years, pipes. Cleaning fixtures helps at the fixture level. See our shower hard water guide for signs and fixes.