Low Water Pressure: Causes and Fixes
Normal household water pressure is 40 to 80 psi, and most homes feel best at 50 to 60 psi. If your shower has gone weak, buy an inexpensive screw-on pressure gauge, thread it onto an outdoor hose bib, and open the valve. Anything under 40 psi is genuine low water pressure. Anything at 50 psi or above means your pressure is fine and the problem is a clog or a restriction somewhere between the meter and the fixture.
That one test splits the whole problem in half, and it takes about two minutes. Most people skip it and start replacing shower heads at random, which is how a free fix turns into a weekend and a return trip to the store.
Updated September 2026
A note on numbers. This page gives specifications, psi targets, diagnostic steps, and the line items that belong on a written plumbing quote, not dollar figures. Plumbing labor is priced locally and repipe bids in particular swing hard by market and by access. What travels is the order of operations: cheapest cause first, repipe last, and only after a plumber has physically shown you the inside of a corroded pipe.
The fixes in this article run from free, like cleaning an aerator, to a whole-house repipe, which is one of the larger projects a house can need. The good news is that the cheap causes are far more common than the expensive ones, and the gauge tells you which half you are in before you spend anything.
Start here: is it one fixture or the whole house?
Before you diagnose anything, walk the house and answer three questions. Write the answers down. They point straight at the cause.
- Is it one fixture, or all of them? One weak faucet is almost never a pressure problem.
- Is it hot only, cold only, or both? Hot only points at the water heater or its shutoff.
- Did it happen overnight, or fade over years? Sudden means a valve, a break, or a failed regulator. Gradual means scale, corrosion, or a slowly dying part.
| What you observe | Most likely cause | Where the fix sits on cost |
|---|---|---|
| One faucet weak, others fine | Clogged aerator or supply stop | Free, or the price of a new aerator |
| One shower weak | Clogged shower head or mixing valve cartridge | Free to clean, cheap part if the cartridge is dead |
| Hot water weak everywhere, cold fine | Heater shutoff partly closed, or sediment and scale | Free to flush, mid if a part has corroded |
| Whole house weak, happened suddenly | Main or meter valve partly closed, failed regulator | Free if it is a valve, mid if the PRV has failed |
| Whole house weak, got worse over years | Galvanized pipe corrosion or heavy scale | The most expensive answer on this page |
| Whole house weak, well system | Pressure switch, waterlogged tank, failing pump | Cheap for a switch, high for a submersible pump |
| Weak only during certain hours | Municipal demand, or an undersized service line | Free to diagnose, call the utility first |
| Pressure fine at the hose bib, weak inside | Restriction after the meter, softener, or filter | Usually a cartridge, the cheapest paid fix here |
Work top to bottom. The cheap causes really are the common ones, and plumbers get called out for closed valves and clogged aerators every single week.
Low water pressure vs low flow: they are not the same thing
This distinction saves people a lot of money, so it is worth 60 seconds.
Pressure is force, measured in psi. It is what the gauge reads with nothing running.
Flow is volume over time, measured in gallons per minute. It is what actually fills your bathtub.
You can have perfect 60 psi pressure and terrible flow, because a pipe is undersized, scaled shut, or partially valved off. You can also have great flow at one fixture and low pressure across the house. They are separate measurements and they fail separately.
Federal fixture standards cap flow on purpose. Shower heads sold in the US are limited to 2.5 gpm, and many efficiency models run 1.5 to 1.8 gpm. Bathroom faucets are commonly 1.2 gpm. If a new shower head feels weak on a house that gauges at 60 psi, you did not lose pressure. You bought a low-flow head. Swapping to a 2.5 gpm model with a pressure-compensating design fixes that for the price of a shower head.
The 10 real causes of low water pressure
Here they are roughly in order of how often they turn out to be the answer.
1. Clogged aerator (single fixture, very common)
The aerator is the small screen in the tip of the faucet. Mineral scale and pipe debris collect there and choke flow to a dribble.
Unscrew it by hand or with tape-wrapped pliers, soak the parts in white vinegar for a few hours, brush the screen, and reassemble. That costs nothing. A replacement aerator is one of the cheapest parts in a hardware store if the old one is chewed up.
2. Clogged shower head or a bad cartridge
Same problem, bigger fixture. Bag the head in vinegar overnight with a rubber band, then run it hot. If cleaning does not help and the temperature is also hard to set, the mixing valve cartridge inside the wall is the culprit. The cartridge itself is a cheap part; having a plumber do the swap costs several times the part, because the trim has to come off and the valve is in the wall.
3. A partly closed valve
Two valves control your whole house: the main shutoff inside near where the line enters, and the curb or meter valve outside. A half-turned main is the number one cause of a sudden house-wide drop, especially right after any plumbing work.
Check that the handle is fully open. On a gate valve that means fully counterclockwise. On a ball valve the lever should sit in line with the pipe. This fix is free.
Do not force a stuck old gate valve. They snap. That turns a free fix into a valve replacement on the main line, which is one of the more annoying small plumbing jobs there is.
4. A failed pressure reducing valve (PRV)
If your street pressure is high, your house has a bell-shaped brass PRV just past the main shutoff. It steps incoming pressure down to something your fixtures can survive.
PRVs last 7 to 15 years. When the internal diaphragm fails they either lock down, dropping pressure everywhere, or stop regulating, letting pressure spike until supply lines start letting go.
- Replacement: a mid-priced plumbing job. The valve is a modest part and the labor is short, but it sits on the main line, so it is priced accordingly.
- DIY: possible for a confident homeowner with soldering or press tools, but a mistake on the main floods the house.
- Adjustment: many PRVs have a top screw. Turning it clockwise raises pressure. Adjust in small turns, re-check the gauge, and never exceed 80 psi.
Eighty psi matters. Most plumbing codes require a PRV once static pressure exceeds 80 psi, and water heater warranties are commonly voided above it.
5. Corroded galvanized steel pipe
Homes piped before about 1960 often have galvanized steel supply lines. Over decades the interior rusts and scales inward until a 3/4 inch pipe has a 1/4 inch opening left.
This is the expensive answer, and it announces itself in a specific way: pressure fell off slowly over years, the hot side is usually worse, and the water runs rusty after a vacation.
You cannot clean it out. The fix is repiping in copper or PEX, and the scope is covered further down.
6. Water heater problems (hot side only)
If cold is strong and hot is weak, stop looking at the house and look at the heater.
- The heater's own cold-in shutoff is partly closed. Free to fix.
- Sediment has built up in the tank bottom. Flushing helps, and it should be done yearly anyway.
- The dip tube or the nipples at the top have corroded and restricted flow. Both are cheap parts with an hour of labor.
- The unit is old, scaled, and near the end. Our water heater repair guide covers which symptoms are worth fixing and which mean replacement.
7. Well system issues
On a private well, pressure is created by a pump and a pressure tank, and it cycles between a cut-in and a cut-out setting, commonly 40/60 or 30/50 psi.
- Pressure switch out of adjustment or failed. The cheapest well repair, and the most common one.
- Waterlogged pressure tank, meaning the bladder failed and the pump short-cycles. A tank replacement, which is a mid-range job.
- Failing pump or a dropping water table. A submersible pump replacement is the most expensive item on the well list, because the pump has to come up out of the casing.
- Clogged well screen or sediment filter. Cheap if it is the filter, a service call if it is the screen.
A telltale for a waterlogged tank: the pump clicks on and off every few seconds while a faucet runs. That short cycling destroys pumps, so do not live with it.
8. A whole-house filter or softener that needs service
Cartridge filters restrict flow badly once loaded. If pressure is good at an outdoor hose bib, which is usually plumbed before the treatment gear, and weak inside, that is your answer.
Change the cartridge. Most need it every 3 to 6 months. Softeners can also stick in bypass or clog in the resin bed, which a service tech can diagnose in a single short visit.
9. A hidden leak
A significant leak drops pressure and raises the bill. Test for one: turn off every fixture, read the meter, wait two hours with no water used, then read it again. Movement means water is going somewhere.
Slab leaks and underground service line leaks are the ugly versions. Service line replacement is priced by length, depth, and whether the crew has to cross a driveway, and crossing hard surface is what moves that bid the most. If the leak is showing up in a basement, our basement leak repair guide separates the plumbing sources from the groundwater sources.
10. Municipal supply and elevation
Sometimes it is not your house. City pressure varies with elevation, time of day, hydrant flushing, and main breaks. Ask a neighbor. If theirs is weak too, call the water utility, which will usually test at the meter at no charge.
Homes at the top of a hill or at the end of a long service run genuinely receive less pressure. That is where a booster pump earns its keep, and a booster with a storage tank costs meaningfully more than a booster alone.
Worked example: diagnosing a 1970s ranch in one afternoon
A homeowner reports weak showers upstairs and a kitchen faucet that trickles. Here is the actual sequence, and notice how much of it is free.
| Step | Time | Who does it | Result |
|---|---|---|---|
| Gauge at the outdoor hose bib | 5 min | Homeowner | Reads 38 psi, so pressure really is low |
| Check main shutoff position | 2 min | Homeowner | Fully open, not the cause |
| Locate PRV, check for a gauge port | 10 min | Homeowner | PRV present, dated 2009, so 16 years old |
| Turn PRV adjust screw 2 turns clockwise, re-gauge | 15 min | Homeowner | Climbs to 42, then drifts back to 38. Diaphragm is failing |
| Clean the kitchen aerator while waiting | 10 min | Homeowner | Kitchen flow doubles. A separate problem, now solved |
| Plumber replaces the PRV | 90 min | Licensed plumber | House now holds 58 psi |
| Re-check every fixture | 10 min | Homeowner | Upstairs shower normal, one head still weak |
| Descale that shower head in vinegar | Overnight | Homeowner | Fixed |
Two of the three problems were free to fix, and the third was a single short plumber visit. The gauge is what kept this from turning into a repipe quote, which is what a salesperson looking at 1970s plumbing and a weak shower will often propose.
What a whole-house repipe actually involves
If the diagnosis really does land on corroded galvanized pipe, this is the project you are facing. Repipe bids track house size, number of bathrooms, and how much wall has to be opened, in that order.
| Home size | Bathrooms | Relative scope in PEX | Copper against PEX |
|---|---|---|---|
| 1,000 sq ft | 1 | The baseline repipe | Copper is roughly 1.5 to 2 times the PEX bid |
| 1,500 sq ft | 2 | Roughly 1.4 times the baseline | Same multiple, on a bigger base |
| 2,000 sq ft | 2 to 3 | Roughly 1.8 times the baseline | Same multiple, and more wall opened |
| 3,000 sq ft | 3 plus | Roughly 2.5 times the baseline | The widest gap, because copper labor scales with fittings |
Those relatives assume a single story with accessible attic or crawl space. Slab homes and multi-story houses sit well above them, because access is the real driver: every foot of pipe a plumber cannot reach becomes drywall that has to come out and go back.
Square footage is the first number every plumber asks for, and it moves the bid more than any other input. Measure it properly with our square footage calculator before you call, so the three quotes you collect are all priced against the same house.
What is not in a repipe price and needs to be, item by item:
- Drywall patching and texture, often a separate trade and a separate line
- Painting after patching, which is almost never included by the plumber
- Permit and inspection, which a repipe always requires
- Fixture, valve and supply-stop replacement while walls are open, which is the cheapest time in the life of the house to do it
Repiping requires a plumbing permit and a licensed plumber in nearly every US jurisdiction. Pressure testing and inspection are part of the process, and unpermitted plumbing work reliably surfaces during a sale. This is not the project to hire off a marketplace listing. If drywall repair lands on your side of the job afterward, our how to patch drywall guide covers the patch and texture sequence.
How to increase water pressure, ranked from cheapest
Try these in order. Stop when the problem goes away.
- Clean aerators and shower heads. Free, and it fixes single-fixture complaints most of the time.
- Fully open the main and every fixture supply stop. Free.
- Change the whole-house filter cartridge. The cheapest paid step on this list.
- Flush the water heater. Free if you do it, a short service call if you do not, and it should happen yearly regardless.
- Adjust the PRV. Free, and never take it past 80 psi.
- Replace the PRV. A short licensed job on the main line.
- Replace old shutoff valves and supply lines at problem fixtures. Priced per fixture, so the total tracks how many are bad.
- Add a booster pump where the utility supply is genuinely weak. A real equipment purchase plus electrical.
- Upsize the service line from the meter to the house. Excavation, so the surface it crosses sets the price.
- Repipe. The largest of these by a wide margin, and only after the diagnosis is certain.
Anything through step 5 is a reasonable DIY afternoon. Steps 6 through 10 involve the main supply line, permits, or both, and belong with a licensed plumber.
Pressure that is too high is the bigger danger
Homeowners chase low pressure and ignore high pressure, which is backwards from a damage standpoint.
Above 80 psi, supply lines burst, toilet fill valves scream, water heaters relieve through the T&P valve, and washing machine hoses fail while nobody is home. High pressure quietly shortens the life of every fixture in the house, and the failures it causes are far more expensive than the regulator that would have prevented them.
If your gauge reads over 80 psi, install or replace the PRV. If it reads over 100, treat it as urgent. A thermal expansion tank on the water heater is also required in many jurisdictions on a closed system with a PRV, because heated water needs somewhere to expand.
While you have the gauge out, leave it on a hose bib overnight. Some gauges have a red drag needle that records the peak. A house that reads 65 psi during the day but spikes to 110 psi at 3 a.m., when city demand drops, is a house with a regulator problem it does not know about.
Frequently asked questions
What is normal water pressure for a house in psi?
40 to 80 psi is the normal range, and 50 to 60 psi is where most homes feel best. Below 40 psi showers feel weak and appliances take longer to fill. Above 80 psi you are damaging fixtures, and most plumbing codes require a pressure reducing valve at that point.
Why is my hot water pressure low but cold is fine?
Nine times out of ten it is at the water heater: a partly closed cold-in shutoff, a tank full of sediment, or a corroded dip tube. Flush the tank first, then check the valve position. If the heater is over 12 years old and heavily scaled, replacement is usually the better use of the money than another repair.
What does replacing a water pressure regulator involve?
A plumber closes the main, cuts the old PRV out, and installs the new one with unions so the next replacement is easier. It is a short job on an accessible main and a much longer one in a tight crawl space or where the surrounding pipe is corroded and has to be rebuilt. Ask for the union detail specifically, since it saves labor every time the valve is serviced.
Can low water pressure fix itself?
Sometimes, if the cause was outside your house. Hydrant flushing, a main break, or a temporary utility repair can drop pressure for hours and then restore it. If yours has been low for more than a day, something in your own system is causing it.
Will a bigger shower head increase pressure?
No. It cannot create pressure, and federal standards cap flow at 2.5 gpm regardless of size. What helps is a pressure-compensating head designed for low-flow conditions, which concentrates the same water into a stronger-feeling spray. It is one of the cheapest upgrades in the house.
Should I install a water pressure booster pump?
Only after you have ruled out clogs, valves, and a failed PRV, and only if the gauge confirms the incoming supply itself is weak. A booster pump on a house with a clogged filter just makes an expensive noise. Confirm with the gauge at the meter side first, then price the pump.
How do I know if my pipes are clogged with mineral buildup?
Slow decline over years, worse on the hot side, rusty water after the house sits unused, and visible corrosion at exposed threaded joints. A plumber can cut a short section of suspect pipe and show you the opening, which is the only way to be certain. Do not authorize a repipe without seeing that section.
Does a water softener reduce water pressure?
A working one costs you only 1 to 5 psi. A softener that has clogged in the resin bed, or a sediment prefilter that has not been changed, can cost you 20 psi or more. Test at an outdoor hose bib upstream of the equipment to isolate it from the rest of the house.
The short version
Buy the gauge first. Under 40 psi is a real pressure problem, and the causes are a valve, a regulator, corroded pipe, or a well component. Over 50 psi with weak fixtures is a clog, and it is usually free to fix in an afternoon with a bottle of white vinegar.
Do the cheap steps in order, and only reach for a repipe quote once a plumber has physically shown you the inside of a corroded pipe. If you do get there, measure the house with the square footage calculator so every bid you compare is built on the same number, and check our DIY home improvement guide for where the line between homeowner work and licensed work actually sits.
