Inside the house
Why has my water pressure suddenly dropped?
A sudden drop in water pressure across the whole house can mean water is escaping from the supply line before it reaches the fixtures, but it is at least as often a pressure regulator, a partly closed valve, or work happening on the provider's system. Whether it affects the whole house or only one tap is the fastest way to sort it.
What it usually is
Whole house or one fixture
A sudden whole-house pressure drop can mean the supply line is losing water before it reaches the house, though a failing pressure regulator is the more common cause.
If every fixture in the house is weak at once, the cause is upstream of all of them: the service line, the main shut-off, the pressure regulator, or the provider's supply. If one tap is weak and the rest are fine, the cause is at that fixture, and it is usually an aerator full of mineral.
A buried leak on the service line can reduce pressure at the house, because water is being lost before it arrives. That version normally comes with other evidence: a meter that moves with everything off, a wet patch somewhere between the meter and the house, or a bill that has climbed.
Be honest about it
What it could be instead
Most sudden pressure drops are not leaks:
- A failing pressure-reducing valve. The single most common cause, and it can drop pressure overnight.
- A valve not fully open. After any plumbing work, the main or the meter valve can be left part-closed.
- Work on the provider's system. Mains repairs and flushing affect a whole street at once.
- A water softener or filter that has clogged or gone into bypass.
- Mineral in the aerators, if it is really only one or two taps.
Narrowing it down
Sorting the causes by what is affected
| What is affected | Most likely cause | What to check first |
|---|---|---|
| Every fixture, hot and cold, at once | Regulator, main valve, or the supply | Ask a neighbour whether theirs dropped too |
| Every fixture, plus a moving meter with everything off | A leak on the service line before the house | Read the meter twice an hour apart |
| Hot water only | The water heater's shut-off, or its inlet | The valve at the heater |
Ten minutes, on your own
Ten minutes to place it
Test a hose bib on the street side of the house
It is usually ahead of the regulator and the softener, so strong pressure there and weak pressure inside points at something between them.
Ask a neighbour
If the whole street dropped, it is the provider's system and the answer is a phone call rather than a visit.
Check the main shut-off and the meter valve are fully open
A valve left part-closed after work is common and costs nothing to rule out.
Read the meter with everything off
Weak pressure plus a moving meter is the combination that points at a leak on the service line.
How urgent is it
Rarely urgent on its own
Low pressure by itself does not damage anything and can wait. It is an inconvenience rather than a risk.
It becomes worth acting on when it arrives with other signs: a moving meter, a wet patch between the meter and the house, a bill that has climbed, or water audible with everything off. That combination points at water escaping before it reaches the house, and that is a leak with a location.
If you call us
What we would look at
We would start where the pressure is, not where it is missing: a gauge on a hose bib to measure what is actually arriving, then the same reading upstream and downstream of the regulator to see whether the regulator is the problem.
If the supply line is suspect, it gets isolated and pressure tested on its own, then listened to and traced. Where the answer is a regulator or a valve rather than a leak, we will say so, because that is not a detection job: water main leak detection.
Straight answers
Water pressure questions
Can a water leak cause low water pressure?
It can, if the leak is on the service line before the water reaches the house. That version almost always comes with a meter that moves with everything off, so the meter test is the quickest way to include or exclude it.
What is the most common cause of a sudden pressure drop?
A failing pressure-reducing valve. It is a wearing part, it can drop the whole house overnight, and it looks exactly like a supply problem from inside the house.
Only my shower is weak. Is that a leak?
Almost certainly not. A single weak fixture is usually mineral build-up in the aerator or shower head, which is ordinary in Valley water and easy to check by unscrewing it.
How can I tell whether it is the water company?
Ask a neighbour. A pressure drop that affects the whole street at once is the provider's system, often planned work, and it is worth a call to them before anything else.
Homes we work in
Tell us what the water is doing
Whether every fixture dropped or only one, whether the street dropped too, and whether the meter moved with everything off.
Tell us what is weak and what is not
Whole house or one tap, hot or cold, and whether the neighbours noticed.
5.0 on Google
What customers in the Phoenix valley have written. The words are theirs, on listings we cannot edit.
“Humberto has been amazing! Prompt, professional, and patient. He has gone above and beyond, taking the time to show me how to operate the water valves and educating me so I can continue to monitor for future leaks. He identified multiple leaks and made thoughtful recommendations.”
“Beto was very professional, thorough and patient in explaining everything he was doing and why. It was an excellent and well worth it experience, and this is saying something for an architect who had a hundred questions!”
“The owner and operator of this company is everything a contractor should be. On time, honest, competent, reachable, comprehensive. Hope to work with him again in the future.”