Why is my water pressure suddenly low?
If the pressure dropped overnight rather than over years, that narrows it down fast. Here's how to tell a fixture problem from a house problem — and which one means calling someone.
Low water pressure is one of those unfortunate problems that's either a ten-minute fix or a genuine repair, and the difference is usually obvious once you know what to check. The single most useful question: is it one tap, or the whole house?
Start here: one fixture, or all of them?
Run the cold tap in the kitchen, then a bathroom sink, then the shower. If only one is weak, the problem is at that fixture and the rest of the house is fine. If everything is weak, the problem is upstream — where water enters the house.
If it's one fixture
Two likely causes, both simple. The aerator — the little mesh screen in the tip of the spout — collects mineral scale and pipe debris. In much of Ocean and Monmouth County the water is hard enough that this happens on a regular schedule.
The other is the supply stop under the sink — the small valve on the wall. These get knocked half-closed during a cabinet clear-out more often than you'd think. Turn it counter-clockwise until it stops.
- Aerator clogged with scale or grit — rinse or replace
- Supply stop partly closed — open it fully
- Cartridge failing in a single-handle mixer — a common cause on showers
- Flexible supply line kinked behind the vanity
If it's the whole house
Now it's worth being systematic, because a few of these matter.
First, find your main shutoff and confirm it's fully open. If anyone has worked on the plumbing recently — including you — a main that was never reopened all the way is the single most common cause of a house-wide drop. Knowing where that valve is before you need it is worth five minutes; see where's your main shutoff.
Second, the pressure-reducing valve. Most homes on municipal water have one where the supply enters, and they wear out — typically after eight to twelve years. When one fails it usually fails toward low pressure, gradually, over weeks.
Third, and this is the local one: if the house was built before about 1970 and still has its original supply piping, that pipe may be galvanized steel. Galvanized corrodes from the inside, narrowing the bore until the flow chokes. Plenty of older shore homes are still on it. That's not a repair, it's a repiping job — but it's also predictable, and worth knowing about before you're mid-renovation.
The version that means call someone
A gradual decline over years is usually scale or a tired regulator. A sudden drop overnight, with no work done and nothing changed, is different — that can mean water is going somewhere it shouldn't.
Hot water only, on the other hand, points at the water heater rather than the supply — usually sediment in the tank or a failing shut-off on it. If it's making noise as well, that's the same underlying cause: see why is my water heater making that noise.
What we'd do
On a house-wide pressure call we test static pressure at an outside spigot, check the regulator against it, and look at the main and the meter. Most of the time it's the regulator and we're done the same visit. If it's a leak, finding it is the job — and we'd rather find it before it finds your ceiling.