Low water pressure: one fixture or the whole house?
Before doing anything else, answer one question: is it one fixture, or the whole house? That single distinction determines whether you are looking at a five-minute cleaning job or something that deserves attention today. Walk the house, run every tap hot and cold, and find out.
If it is one fixture
The aerator is the small screened cap at the tip of the spout, and it is the answer far more often than anything else. Sediment, mineral scale, and small fragments dislodged from pipes collect there. Unscrew it — by hand, or with pliers padded by a cloth so you do not chew up the finish — photograph the parts in order before you separate them, rinse and brush the screen, and soak it in white vinegar if it is scaled. Many low-pressure complaints end here.
If the aerator is clean and flow is still poor, check the shutoff valves under the sink; they get bumped by stored items and end up half closed. Beyond that, the cartridge inside the faucet body can clog or fail, which is a replaceable part on most fixtures if you can identify the make and model. Showerheads are the same story: unscrew, descale, and clear the individual jets.
A special case worth recognising: poor flow at only the hot side of one or several fixtures. That points upstream to the water heater or its shutoff valve, particularly on older tanks where sediment accumulates. If that heater is also showing any sign of leaking, deal with that first.
If it is the whole house
Check the main shutoff is fully open
It sounds too simple, and it is regularly the answer — especially after any recent plumbing work, when a valve gets restored to almost-open rather than open. Follow the supply line to where it enters the house and confirm the valve is at its full travel. Check the valve at the meter too, where you have access.
Look for a pressure reducing valve
A bell-shaped brass fitting near the main entry, usually with an adjustment screw on top. These have a service life, and when they fail they can drop household pressure gradually enough that nobody notices until showers are unpleasant. They can also fail the other direction, sending damaging pressure into the house. Replacement is a plumber’s job.
Ask the neighbours
If houses nearby are also affected, it is the utility’s side — a main break, hydrant work, or scheduled maintenance. That is a phone call, not a repair. Municipal pressure also varies naturally by elevation and time of day.
Check for a leak at the meter
Turn off every fixture and appliance that uses water, then look at the meter. Many have a small triangular or star-shaped low-flow indicator that spins with even minimal flow. If it is moving with everything off, water is escaping somewhere — and a supply-side leak between the meter and the house is usually the homeowner’s responsibility.
Consider the pipes themselves
In older homes with galvanised steel supply piping, decades of internal corrosion narrow the effective diameter until flow suffers everywhere. This is a gradual decline rather than a sudden drop, and the fix is repiping. If you have a home of that vintage and pressure has been slowly getting worse for years, this is the likely explanation.
Wells are a different system
On a private well, pressure is produced by a pump and buffered by a pressure tank, and the symptoms differ. Pressure that fluctuates rapidly or a pump that switches on and off in quick succession — short cycling — commonly indicates a waterlogged pressure tank that has lost its air charge. Consistently low pressure can indicate a failing pump, a clogged well screen, or a dropping water table. Well systems deserve a specialist rather than a general plumber.
- Cleaning aerators and showerheads
- Checking fixture shutoffs and the main valve
- Measuring pressure with a hose bib gauge
- Reading the meter to test for a hidden leak
- Pressure reducing valve replacement or adjustment
- A meter still turning with everything off
- Galvanised pipe replacement or repiping
- Well pumps and pressure tanks
Why this is worth chasing
Low pressure is annoying. What sits behind it is sometimes not. A leak running between the meter and the house can cost a great deal before it surfaces; a failed PRV can quietly subject every connection in your plumbing to more pressure than it was designed for; and corroded supply piping is a planning problem, not an emergency, but only if you know about it early enough to plan. Fifteen minutes with a gauge and a look at the meter answers all three.
What homeowners argue about online
The Reddit argument here is about the pressure reducing valve: whether you should just turn the adjustment screw yourself. It has a screw, it is right there, and turning it does change the pressure — so the advice splits between people who did it successfully and plumbers telling them not to.
Adjusting one is not difficult. The problem is that a PRV which has drifted low is usually not out of adjustment; it is wearing out. Cranking the screw on a failing valve buys back some pressure for a while and hides the fact that the part is on its way out, and PRVs can fail in the other direction too — sending pressure into the house that every fixture, supply hose, and appliance connection then has to live with.
The step both camps agree on, and almost nobody takes, is to measure first. A gauge that threads onto a hose bib costs very little and turns the whole argument into a number. Adjust against a reading, not against how the shower feels — and if the valve will not hold the pressure you set, that is a replacement, not an adjustment.
Write it down while it’s fresh
A single dated pressure reading is worth far more than it looks. On its own it is a number; taken again a year later, it is the difference between “it feels weaker lately” and a measurable change you can act on.
- Measured static pressure, with the date — so you can compare later
- Location of the main shutoff, the meter, and any PRV
- Supply pipe material and approximate age
- Faucet and showerhead makes and models, for cartridge parts
- Date of the last aerator cleaning or fixture repair
- For wells: pump and tank make, model, install date, and service history
This is the part almost everyone skips, and it’s the part that pays. The next time this happens — or when a warranty claim, an insurance adjuster, or a buyer’s inspector asks — the answer is already written down. That is what homwarden is built to hold: maintenance, appliances, warranties, receipts, and records, filed with the equipment they belong to.
Common questions
Why is my water pressure suddenly low?
A sudden drop across the whole house usually points to a partially closed main or meter valve, a failing pressure reducing valve, or a supply-side issue from the utility. A drop at one fixture is nearly always a clogged aerator, a blocked cartridge, or a partly closed shutoff at that fixture.
Is low water pressure a sign of a leak?
It can be. If pressure has dropped noticeably with no other explanation, check your meter with every fixture off — if the meter is still registering flow, water is going somewhere. That is a leak to find promptly, and it is one of the more expensive things to leave running.
How do I clean a faucet aerator?
Unscrew the small screen assembly from the faucet tip by hand or with pliers padded by a cloth, then rinse and brush out the debris. Mineral scale generally releases after soaking in white vinegar. Reassemble the parts in the same order, which is why photographing them before disassembly is worth the ten seconds.
What is a pressure reducing valve and does my house have one?
A PRV is a bell-shaped brass valve near where the main supply enters the house, used to lower incoming municipal pressure to a safe household range. They have a finite service life, and a failing one can cause either a gradual pressure drop or dangerously high pressure. Not every home has one.
General maintenance guidance only. It is not a substitute for an inspection, a licensed contractor, an engineer, your insurer, the manufacturer’s instructions, or local code. When the stakes are gas, fire, structure, or standing water near electricity, stop and call a professional.