A sudden drop in water pressure is easy to notice — showers turn to trickles, faucets take forever to fill a pot, and washing machines run much longer. Low water pressure is rarely an emergency, but it almost always points to a real problem somewhere in your plumbing. The challenge is that the cause can be as simple as a clogged aerator or as serious as a hidden leak or corroded pipe. Working through the causes in order, from cheapest to most complex, will help you identify the culprit and decide whether you need professional help.
Before changing anything, check whether the pressure problem affects the whole house or just one fixture. This single observation narrows the list of possible causes dramatically.
If only a single faucet, shower, or toilet has low pressure, the problem is almost always local. The most common cause is a clogged aerator, the small mesh screen screwed onto the end of faucets. Mineral deposits and sediment collect in the screen over time and restrict flow. Unscrew the aerator, rinse it under water, scrub it with an old toothbrush, and soak it in vinegar if deposits are stubborn. Reinstall it and test the flow — this simple fix restores pressure in the majority of cases.
Showerheads have the same issue. Mineral scale blocks the nozzles, especially in areas with hard water. Remove the showerhead, soak it in vinegar overnight, and brush out the openings. If pressure improves only with the showerhead removed, scale in the head was the culprit.
If all fixtures in a single bathroom have low pressure but the rest of the house is fine, suspect a problem in that room's supply lines — a partially closed shutoff valve under the sink, a failing pressure-balanced shower valve, or a kinked supply tube. Check the shutoff valves first; they can be accidentally bumped partially closed during cleaning or repairs.
When pressure is low everywhere, the cause is upstream of your fixtures. Possibilities include a partially closed main shutoff valve, a failing pressure regulator, a leak in the main supply line, or buildup inside the pipes themselves. Start by finding your main shutoff valve — usually near the water meter — and confirming it's fully open.
Homes with a pressure regulator maintain steady water pressure from the municipal supply. Regulators wear out after years of service, and a failing regulator typically causes a gradual, whole-house pressure decline. A plumber can test the regulator with a pressure gauge and adjust or replace it. If you notice pressure changing throughout the day, this is frequently the cause.
A leak in a supply line or the main service line can reduce pressure while also wasting water and money. Check for signs of a leak: unexpectedly high water bills, damp patches on floors or walls, the sound of running water when everything is off, or unusually green grass over your buried service line. If you suspect a leak, call a professional to locate and repair it before it causes structural damage.
Older galvanized steel pipes accumulate mineral deposits and rust on the inside, slowly reducing the pipe's diameter and your water pressure. This is a long-term issue that builds over decades, and it's common in homes with hard water. Patching the problem is difficult — pipes often need replacement, which a plumber can assess after inspecting the system.
Low water pressure is sometimes confused with slow drainage, but the two often occur together. If water leaves a tub or sink very slowly, it can feel like the water pressure is weak even when the supply is fine. A partially clogged drain holding water in the basin is usually the real issue. Clearing the drain — whether with a plunger, chemical-free methods, or professional cleaning — restores both flow and the feeling of normal pressure.
Similarly, if your drains and toilets are slow across the whole house, the problem could be in the main line rather than the supply. A partial sewer line obstruction can cause gurgling and slow draining throughout the home, and it won't improve until the line is cleared professionally.
Some causes of low water pressure are worth tackling yourself, but others need professional equipment. Call for help when you notice any of the following:
Professionals diagnose stubborn pressure problems with tools you won't have at home. A video camera inspection can confirm whether your supply or drain lines have scale buildup, breaks, or other damage. Plumbing pros can also test and replace pressure regulators and locate hidden leaks without tearing up your property. For routine maintenance, our guide on how often to clean drains can help you keep the whole system healthy.
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