Where the Problem Usually Starts

Low water pressure in your house usually comes from one of three places: the municipal supply line, the pressure regulator on your main water line, or a blockage somewhere inside your home's pipes. Before you call a plumber, you can check which one is causing the problem yourself.

Start by turning on a faucet in your kitchen and another in a bathroom at the same time. If both run weak, the problem is likely at the meter or regulator. If only one runs weak, the blockage is probably in that line or fixture. If all your hot water runs weak but cold water is fine, the issue is in your water heater or its supply line.

The municipal supply line is not something you can fix yourself — that is the water company's responsibility. But the regulator and blockages are things you can address or at least understand before paying for service.

Key Takeaways

  • A pressure regulator that is set too low can be adjusted upward by turning the adjustment screw on top, though you should check your local code first because some areas have maximum limits.
  • Sediment buildup in aerators (the screens at faucet tips) is the most common cause of weak pressure at a single fixture and takes five minutes to clean.
  • Mineral deposits inside water heaters reduce pressure on hot water lines; flushing the tank once a year prevents this.
  • Leaks in your supply line waste pressure and water; if you suspect one, check your meter reading before and after two hours of no water use.
  • If pressure is weak everywhere and your regulator is not the cause, the municipal supply may be low, which you can confirm by calling your water company.

Adjusting Your Pressure Regulator

The pressure regulator is a bell-shaped or cylindrical device mounted on the main water line where it enters your house, usually near the meter. It keeps pressure from the street from damaging your pipes. If it is set too low, your whole house will have weak pressure.

To check the current pressure, buy a water pressure gauge (about $10 at any hardware store) and screw it onto an outdoor faucet or a laundry sink faucet. Normal household pressure is 40 to 60 pounds per square inch (psi). If your gauge reads below 40 psi, the regulator may need adjustment.

Locate the adjustment screw on top of the regulator — it looks like a large bolt with a locknut underneath. Turn the screw clockwise to increase pressure. Make a quarter-turn, then test the pressure again with your gauge. Keep adjusting in small increments until you reach 50 to 55 psi. Do not exceed 80 psi, as that can damage fixtures and appliances. Once you have the pressure where you want it, tighten the locknut so the adjustment does not shift.

Before you adjust, check your local plumbing code or call your water company, because some municipalities set maximum pressure limits for residential lines. If your regulator is broken or you are not comfortable working with it, a plumber can replace it for $300 to $500.

Cleaning Aerators and Screens

An aerator is the small screen at the tip of your faucet. Sediment, rust, and mineral deposits collect there and block water flow. This is the easiest problem to fix and often solves weak pressure at a single sink or shower.

Unscrew the aerator by hand or with a wrench if it is stuck. Hold it up to the light — if you see white, tan, or rust-colored buildup, that is your problem. Rinse it under running water and use an old toothbrush to scrub away deposits. For heavy mineral buildup, soak the aerator in white vinegar for two hours, then scrub again.

If the aerator is too corroded to clean, replace it with a new one (about $3 to $8). Screw it back on by hand until it is snug, then test the pressure. Repeat this for every faucet that has weak pressure. Shower heads work the same way — unscrew the head, clean or replace the internal screen, and screw it back on.

Flushing Your Water Heater

If only your hot water pressure is weak, sediment inside the water heater is likely the cause. Over time, minerals settle at the bottom of the tank and reduce the space available for water, which lowers pressure on the hot water line.

Flushing the tank once a year prevents this buildup. Turn off the power to the heater (flip the breaker for electric, or turn the gas valve to pilot for gas). Attach a garden hose to the drain valve at the bottom of the tank and run the other end to a floor drain or outside. Open the drain valve and let the tank empty completely — this takes 30 minutes to an hour. Close the drain valve, remove the hose, turn the power back on, and refill the tank by opening the cold water inlet valve.

If you are not comfortable doing this yourself, a plumber can flush the tank for $150 to $300. If flushing does not restore pressure, the heater may be failing and need replacement.

Finding and Fixing Leaks

A leak in your supply line wastes both water and pressure. If pressure is low everywhere and your regulator is not the problem, a hidden leak is worth investigating.

Turn off all water use in your house — no showers, no laundry, no faucets. Write down the number on your water meter. Wait two hours without using any water. Check the meter again. If the number has changed, you have a leak somewhere in your line.

Leaks before the meter are the water company's responsibility. Leaks after the meter are yours. If the leak is underground or inside a wall, you will need a plumber with leak detection equipment to find it. A plumber can use acoustic sensors or dye to locate the leak, then cut into the wall or ground to repair it. The cost depends on location and severity, but expect $500 to $2,000 for detection and repair.

When to Call a Plumber

Call a plumber if pressure is low everywhere, your regulator is set correctly, and you have no leaks. The problem may be in the main line or at the meter, which requires professional tools and access to the water company's records.

Also call a plumber if you are uncomfortable adjusting the regulator, if cleaning aerators does not help, or if pressure drops suddenly after being normal. Sudden pressure loss can signal a burst pipe or a major leak that needs when ready attention.

Get a quote from at least two plumbers before you hire one. Most charge $100 to $200 for a service call plus the cost of any repairs. Ask whether they charge for the diagnosis separately or roll it into the repair cost if you hire them to fix the problem.

Frequently Asked Questions

Can low water pressure damage my pipes or appliances?

Low pressure itself does not damage pipes, but it can be a sign of a leak that wastes water and money. Very high pressure (above 80 psi) can damage fixtures, valves, and appliances like dishwashers and water heaters, which is why the regulator exists.

Why is my water pressure low only in the morning?

Morning low pressure often happens because the water company is running maintenance on the main line or because demand is high in your neighborhood. Call your water company to ask if they are doing work. If not, the problem is likely in your house — check your regulator and look for leaks.

Does a water pressure booster pump really work?

Yes, but only if your municipal pressure is genuinely low (below 30 psi). A booster pump costs $500 to $1,500 installed and uses electricity to push water through your lines. Before buying one, have a plumber confirm that low municipal pressure is the actual problem, not a regulator issue or leak.

Will cleaning my aerator fix weak shower pressure?

Often yes. Unscrew the shower head, clean the screen inside, and screw it back on. If that does not work, the problem is in the supply line to that shower, and you may need a plumber to check for blockages or leaks in the wall.

How often should I check my water pressure?

Check it once a year as part of routine home maintenance, or whenever you notice pressure dropping. A sudden drop is worth investigating right away because it can signal a leak or a regulator failure.