You can feel or hear itCommon

Why did my water pressure suddenly drop?

Sudden is the useful word. A gradual decline points at wear; an overnight drop points at something that moved, opened, closed or broke. Four causes fit, and the two questions that separate them cost nothing to answer.

Also covers water pressure dropped overnight · lost water pressure suddenly · pressure fine yesterday, low today

Free check: Ask a neighbor
Free check: Watch the meter with everything off
Most often left partly closed: The valve at the meter, after utility work
Hidden leak repair: $400–$1,500 depending on access
The only cause that worsens while you decide: A hidden leak

Narrow it down

Which of these fits what you are seeing?

Two of these cost nothing to check, and between them they rule out most of the expensive causes.

Likely reasons

What else it could be

Ranked for the common case. Answer the question above and we re-rank for yours.

A valve isn’t fully open
Most common
Water reaches your house through a series of valves: the utility's curb stop at the property line, the valve at your meter, and your main shutoff inside. Any of them partly closed throttles the whole house, and they get left that way after repairs, meter work, or utility visits.
Common misdiagnosis
A lever valve at 45 degrees looks roughly open and reads as "on" to most people. It isn't. In line with the pipe, or it's restricting you.
What it costs you, and how to fix it
If you leave it
No damage, but you may spend money diagnosing a problem that a quarter-turn fixes.
What to expect
Check your main shutoff first: a gate valve (round handle) should turn fully counter-clockwise until it stops; a ball valve (lever handle) is open only when the lever is in line with the pipe, not at an angle.
Then check the valve at the meter, which is the one most often left partly closed after utility work.
The curb stop at the property line belongs to the utility; call them rather than turning it yourself.
Leak somewhere in the system
Water escaping before it reaches your taps costs you both pressure and volume, and a leak inside a wall, under a slab, or in the buried service line can run a long time unnoticed while doing real damage.
Common misdiagnosis
Weak pressure gets blamed on the city or a regulator while a leak runs unchecked. The meter test costs nothing and rules it in or out.
What it costs you, and how to fix it
If you leave it
Unlike most causes here, this one damages your house while you decide. Structural damage, mold, and a climbing water bill all compound.
What to expect
A plumber locates the leak (acoustic and pressure-testing equipment for hidden ones) and repairs it. Main water line repairs commonly run $400–$1,500 depending on location and access. Bring your meter-test result; knowing a leak is confirmed saves diagnostic time you'd otherwise pay for.
Regulator failing or drifting
A regulator works with a spring and a rubber diaphragm. Both wear. As they do, the valve stops holding a steady setting, pressure drifts down over months, swings unpredictably, or in some failures climbs instead.
Common misdiagnosis
Slow decline over months gets blamed on "the city." A gauge test at an outside tap settles it in five minutes, and if the reading is low with no municipal issue, the regulator is the first suspect.
What it costs you, and how to fix it
If you leave it
A drifting regulator can fail toward high pressure as well as low, which brings the damage described above. It also masks other problems by making everything mildly wrong.
What to expect
A plumber can sometimes adjust a regulator that's merely out of adjustment, which costs less than replacement. Most genuinely failing units need replacing: roughly $300–$650 installed. Ask for a before-and-after gauge reading so you can see what you paid for.
It’s the utility, not your house
Sometimes nothing in your home is wrong. Main breaks, scheduled maintenance, hydrant flushing, and peak demand periods all reduce pressure across a whole area.
Common misdiagnosis
The reverse error is more expensive: assuming it's municipal when it isn't, and living with low pressure for months. Ask a neighbour before you assume.
What it costs you, and how to fix it
If you leave it
Nothing to ignore. This resolves when the utility resolves it. Discoloured water afterwards is common as disturbed sediment settles; running a cold tap for a few minutes usually clears it.
What to expect
Check your water utility's alerts or outage page, and call their service line if there's no notice posted. Worth doing rather than waiting: they may not know yet, and reports help them locate breaks.
If your neighbours recover and you don't, come back; at that point the problem has become yours, and we'll pick it up from there.
Debris after recent plumbing work
Plumbing work loosens things. Solder beads, pipe scale, PVC shavings, and rust flakes get flushed downstream and land in the first narrow place they meet: usually the aerators and screens at fixtures nearest the work.
Common misdiagnosis
People assume the plumber "did something wrong." Usually the work was fine and the debris was already in the pipes waiting to be dislodged.
What it costs you, and how to fix it
If you leave it
Debris also reaches appliance inlet screens and toilet fill valves, where it causes slow filling and running toilets that get blamed on the appliances themselves.
What to expect
Remove and rinse the aerators at the affected fixtures, then check the small inlet screens where the washing machine and dishwasher hoses connect. Flush the lines by running cold water with the aerators removed for a minute or two; that pushes remaining debris out rather than into the next screen. Reinstall and re-test.
One thing worth saying: if the work opened your system and you're on a well, ask about testing your water afterwards. Anything that opens a well system can introduce bacteria, which is a separate question from pressure.

Freezing weather, and a tap gives a trickle or nothing? Stop and start with the safety check. Frozen pipes most often rupture as they thaw, and the wrong thawing method is the leading cause of house fires from this. Water escaping from a burst pipe? Shut off the main valve now, then call a licensed plumber.

What this means

What this means for you

Changes with your answer above. Then two ways to know for sure.

Two of these four cost nothing to rule out, and one of them, unlike most causes here, keeps getting worse while you think about it. So the order matters. Ask a neighbor, then watch your meter with every tap shut. Those two questions separate “not your problem” from “deal with this today”.

Everything else can wait until you know which one you have.

Most of what’s on this page comes down to two things you can check yourself, today, for almost nothing:

Start hereFree

Rule out the two cheapest answers

Ask a neighbor
If the whole neighborhood has lost pressure too, the problem is most likely outside your house.
Watch the meter
Shut every tap and monitor the meter. A meter that still creeps means water is escaping, and a hidden leak is the only cause here that gets worse while you decide.

If both come back clear, the problem sits on your side of the meter. That is the point to call a plumber.

Ground truth

Measure your pressure twice, day and night

Screw a gauge onto an outside tap and take one reading in the daytime, one late at night. City pressure often rises overnight as demand falls, so a much higher night reading can point to a missing or failing regulator.

A pressure gauge is an inexpensive hardware-store part.

What your reading meansUnder 50Below the range to aim for50 to 60The range to aim forOver 80Above the code ceilingThe 80 PSI ceiling is code, not opinion: the plumbing code caps static pressure there and requires a regulator above it.

Pressure Fix

Narrow down my cause

This page lists what usually causes sudden loss of water pressure. The tool asks a few questions about your own system and ranks them for what you actually have, cheapest checks first. It starts with a safety screen, every time.

City or town water
Whole house
Neighbors fine
Sudden drop

Your answers come with you.No account, no email. Skip any question you cannot answer.

Start Pressure Fix →

Quick questions

The questions people ask next

How do I tell a leak from a supply problem without paying anyone?

Shut every tap and water-using appliance off, then watch the meter. If it still creeps, water is going somewhere. That test costs nothing, and a confirmed leak saves diagnostic time you would otherwise pay a plumber to spend.

The neighbors are fine. Does that rule out the city?

Largely, and that is why it is the first question. If the street is fine and you are not, the problem may sit on your side of the meter. It works in reverse too: if your neighbors recover and you do not, what looked like a city problem has become yours.

It happened right after the utility worked on the street. Coincidence?

Usually not, and usually not their mistake either. The valve at the meter is the one most often left partly closed after utility work, and work upstream dislodges debris that lands in your aerators. Both are free to check.

Should I call the water company or a plumber first?

Ask a neighbor first, because that one question decides which. If the street has it, call the utility. If it is only you, call a plumber and bring your meter-test result.

Can low pressure damage anything?

Low pressure itself is an annoyance rather than a hazard. The exception is the cause behind it. A hidden leak damages the building while you decide, which is why the meter test comes early.

Pages that often come up alongside this one.

These are likely causes based on what people commonly describe, a place to start, not a diagnosis, and not medical advice. For anything health-related, a certified lab test and your local health authority are the ones to trust.

Why did my water pressure suddenly drop?

Which of these fits what you are seeing?

What else it could be

A valve isn’t fully open

Leak somewhere in the system

Regulator failing or drifting

It’s the utility, not your house

Debris after recent plumbing work