Low Water Pressure in the Whole House: Causes and Fixes

Low water pressure throughout the whole house usually points to something on the main line rather than a single fixture. Common causes include a partly closed main valve, a failing pressure regulator, a problem with the city supply, a leak, or old, corroded pipes. A pressure gauge on an outdoor spigot is the best first check.

If the pressure dropped suddenly and you hear water running with every tap off, or see water pooling, treat it as a possible leak. Close the main water valve, and keep clear of any water near outlets, cords or appliances. The CDC says never to turn power on or off while standing in water (CDC). See our guide to a burst pipe for the next steps.

Is the low pressure everywhere, or just one fixture?

Start by narrowing it down. This one check tells you where to look.

• Just one faucet or shower: The problem is likely in that fixture. This Old House says single-fixture problems usually come from clogged aerators or showerheads, caused by mineral buildup or debris (This Old House). Unscrew the aerator or showerhead and clean it. This Old House suggests soaking them in vinegar overnight.
• Only the hot water, everywhere: The likely cause is on the water heater side, like sediment in the tank or a partly closed valve on the heater. This Old House suggests flushing the water heater according to the owner's manual (This Old House). If you're not comfortable with hot water work, ask a pro. See our guide to no hot water for more on water heaters.
• Hot and cold, everywhere in the house: That's a whole-house problem, and the rest of this guide is for you.

What is normal water pressure?

This Old House says the ideal range for most homes is between 30 and 80 psi, with around 50 psi giving the best performance (This Old House). A reading in the 40 to 60 psi range points away from a whole-house problem.

How to test your water pressure

You can buy a simple pressure gauge that screws onto a garden hose spigot at most hardware stores. This Old House describes the test (This Old House):

1. Turn off every faucet, appliance and fixture that uses water inside and outside.
2. Screw the gauge onto an outdoor spigot, ideally the one closest to where the main line enters the house.
3. Open the spigot all the way and read the gauge.

Write down the number. It helps a pro understand the problem, and it lets you tell if a fix worked.

What causes low water pressure in the whole house?

Here are the common causes, roughly from the simplest to check to the most involved.

1. The main shut-off valve is partly closed

This is common after plumbing work, when someone closes the main valve and doesn't open it all the way again. This Old House lists a partly closed main valve as a cause of whole-house low pressure (This Old House).

What you can check: Find your main shut-off, usually where the main line enters the house. For a round wheel (gate valve), This Old House says to turn the handle counterclockwise until it stops. For a lever (ball valve), the handle should run parallel to the pipe (This Old House). If the valve is old and stiff, don't force it. Old valves can break, and that's a pro's job.

2. A problem with the city supply

Sometimes the problem isn't in your house at all. This Old House lists municipal supply problems as a cause (This Old House). Water main breaks, repairs and high demand can all lower pressure for a whole street.

What you can check:

• Ask a neighbor whether their pressure is low too.
• Look for notices from your water utility, or call their customer line.
• If the utility recently worked on your meter, ask whether the meter valve is fully open.

If you're on a private well, the city isn't a factor. Low pressure on a well usually points to the pump, the pressure tank or its switch, which a well or pump specialist can check.

3. A failing or misadjusted pressure regulator

Many homes have a pressure regulator, sometimes called a pressure-reducing valve or PRV, near where the main line enters the house. It lowers high street pressure to a safe level for your pipes. When it wears out or slips out of adjustment, it can cut the pressure for the whole house.

Fixr says water pressure issues are generally related to the regulator needing to be replaced (Fixr). This Old House also lists a faulty or misadjusted regulator as a cause (This Old House).

This Old House describes adjusting a regulator by turning its screw in small steps and retesting. Since a wrong setting can push pressure too high, it's reasonable to leave the adjustment to a pro, especially if you're not sure the regulator is the problem.

• Pressure regulator replacement: $250 to $1,000 (Fixr).

4. A leak in the main line or under the house

A leak lets water escape before it reaches your taps. This Old House says even small leaks can significantly affect pressure (This Old House).

Fixr lists these signs of a water main leak (Fixr):

• a sudden increase in your water bill with no visible leak;
• wet spots or flooding in the yard;
• the sound of running water when all taps are off;
• discolored or rusty water;
• a sudden drop in water pressure.

In homes built on a concrete slab, a leak can also be under the floor. Fixr lists low pressure throughout the home, high water bills and the sound of running water among the signs of a slab leak (Fixr). See our guide to slab leak repair costs for more.

A simple meter test: The EPA suggests checking your water meter before and after a two-hour period when no water is being used. If the reading changes, a leak is likely (EPA WaterSense).

5. Old, corroded pipes

Many older homes still have galvanized steel pipes. This Old House says they "are prone to corrosion over time," and lists reduced water pressure throughout the home as a sign of pipe damage (This Old House). As the inside of the pipe corrodes and builds up, there's less room for water to flow.

If your home has galvanized pipes, there's a second reason to pay attention. The EPA says lead particles can attach to the surface of galvanized pipes and, over time, enter your drinking water (EPA). Your water utility can tell you how to get your water tested.

This Old House suggests replacing galvanized pipes with copper or PEX as a long-term solution (This Old House).

What if the pressure dropped suddenly?

A slow decline over months or years points toward corrosion or a regulator wearing out. A sudden drop is different. It's more likely to be:

• a city water main break or repair on your street;
• a valve someone closed partway during recent work;
• a regulator that failed;
• a new leak, especially if it came with the sound of running water or a wet spot.

Fixr lists a sudden drop in water pressure among the signs of a water main leak (Fixr). If you suspect a leak, close the main valve and call a plumber. If you're not sure, check with your water utility first, since a street-wide problem usually clears up once the city finishes its work.

What can you safely check yourself?

Here's a simple order to work through:

1. Check whether the problem is one fixture, hot water only, or the whole house.
2. Ask a neighbor or your water utility whether there's a supply problem.
3. Make sure the main shut-off valve is fully open, without forcing it.
4. Test the pressure with a gauge on an outdoor spigot.
5. Do the two-hour meter test to check for a hidden leak.
6. Look for wet spots in the yard, damp floors, or water stains on walls and ceilings.
7. Clean aerators and showerheads if only some fixtures are weak.

What to leave to a pro: adjusting or replacing a pressure regulator, working on a stiff or leaking main valve, finding a hidden leak, and anything involving digging or opening walls.

When should you call a pro?

Call a pro if:

• the pressure is low everywhere, the main valve is open, and the city supply is normal;
• your gauge reads well below the 30 to 80 psi range This Old House gives;
• the meter test shows water moving with everything off;
• you hear running water, see wet spots in the yard, or your water bill jumped;
• the water looks rusty or discolored;
• your home has galvanized pipes and pressure has been getting worse over time.

If pressure is very high instead, that's worth a call too, because it puts stress on pipes, fixtures and the water heater.

Not sure where to start? Bellwick's free check asks where the pressure is low and shows the likely causes, typical costs and questions to ask. Check my plumbing.

What will a pro check?

A plumber will usually:

• test the pressure at a spigot and at fixtures inside;
• check the main shut-off valve and the meter valve;
• test and adjust or replace the pressure regulator;
• look for leaks on the main line and inside the house, sometimes with leak detection equipment;
• check what the pipes are made of and how corroded they are;
• for hot water only, check the water heater, its valves and sediment.

Ask them to share the pressure reading before and after any fix.

How much does it cost to fix low water pressure?

As of 2026, here are national ranges. Local prices vary.

• Fixing a low water pressure problem on the main line: $250 to $4,000 (Fixr).
• Pressure regulator replacement: $250 to $1,000 (Fixr).
• Shut-off valve repair: $150 to $300 (Fixr).
• Shut-off valve replacement: $250 to $1,000 (Fixr).
• Water main line repair: $500 to $2,000, with a national average of $1,000 (Fixr).
• Main water line leak: $500 to $4,000 (This Old House).
• Main water line replacement: $1,500 to $12,000, with an average of $3,750 (Fixr).
• Slab leak detection: $100 to $400 (Fixr).
• Slab leak repair: $1,000 to $4,000, with a national average of $2,500 (Fixr).
• Whole-house plumbing: $10,000 to $20,000 (This Old House).
• Water heater low pressure problems: $75 to $500 (Fixr).

The cheapest fixes, an open valve or a city supply problem that clears up, may cost nothing at all. That's why the simple checks come first.

Should you repair or replace the pipes?

For most homes, a single repair fixes the problem: opening a valve, replacing a regulator or fixing a leak. Replacing pipes is worth discussing when:

• the home has old galvanized pipes and pressure keeps getting worse;
• the water is often rusty or discolored;
• you've had several leaks in different places;
• a camera or inspection shows heavy corrosion.

Ask for a written quote for both a targeted repair and a larger replacement, so you can compare.

Questions to ask before you approve the work

• What pressure did you measure, and where?
• What do you think is causing it, and how did you confirm it?
• Is the pressure regulator working, and what is it set to?
• Is there any sign of a leak on the main line or under the house?
• What are my pipes made of, and are they in good shape?
• Can I get the price in writing before you start?
• Is there a service-call fee, and does it go toward the repair?
• Is your work guaranteed, and for how long?
• Are you licensed and insured for this work where I live?

The bottom line

When the pressure is low everywhere, start simple. Check with a neighbor or your water utility, make sure the main valve is fully open, and test with a gauge. A healthy home usually reads between 30 and 80 psi. If those check out, the likely causes are a worn pressure regulator, a hidden leak or old, corroded pipes, and a pro can test for each. Watch for signs of a leak, like running water with every tap off or a jump in your water bill, and shut off the main valve if you find one.

When you're ready, check my plumbing to see the likely causes and questions to ask.