Check Your Main Water Shut-Off Valve First

The fastest fix for low water pressure is often a valve you can adjust yourself. Your main water shut-off valve — the one that controls water flow into your entire house — may be partially closed. This valve sits where the water line enters your home, usually in the basement, crawl space, or near the foundation. It looks like a round knob or a lever handle.

If it's a round knob, turn it counterclockwise (left) a quarter turn at a time until pressure improves. If it's a lever, it should point in the same direction as the pipe when fully open. Do not force it — you're looking for smooth resistance, not a stuck valve. This single adjustment solves the problem in roughly one out of every five low-pressure calls.

After adjusting, turn on a faucet in your lowest-floor bathroom and a faucet on your highest floor. Both should have similar pressure. If the upper floor is still weak, the problem is elsewhere in your system.

Key Takeaways

  • Your main shut-off valve may be partially closed — turning it counterclockwise can restore pressure without calling a plumber.
  • Sediment buildup in your water heater or pipes reduces pressure over time and can be flushed out with basic tools.
  • A clogged aerator (the screen at the faucet tip) affects only that faucet, while low pressure everywhere points to a valve or supply line issue.
  • Water pressure regulators fail gradually and can be replaced for $150 to $300 by a plumber, or you can test yours with a gauge first.
  • Leaks in buried water lines are expensive to fix but show up as unusually high water bills or soft spots in your yard.

Flush Sediment from Your Water Heater

Mineral deposits and sediment collect at the bottom of your water heater over years of use. This buildup narrows the outlet pipe and reduces hot water pressure — sometimes cold water pressure too if the sediment is severe. Flushing the tank takes 30 to 45 minutes and costs nothing beyond the water you drain.

Turn off the water heater at the breaker or gas valve. Attach a garden hose to the drain valve at the bottom of the tank and run it to a floor drain or outside. Open the drain valve slowly — water will be hot — and let the tank empty completely. You'll see brown or gray sediment pour out at first; keep draining until the water runs clear. Close the drain valve, turn the water back on, and restore power to the heater. Pressure should improve within an hour as the tank refills.

If you have an older water heater (more than 10 years) and sediment is heavy, flushing may not restore full pressure. In that case, the heater itself may need replacement.

Clean or Replace Clogged Aerators

An aerator is the small screen screwed onto the tip of your faucet. It mixes air into the water stream and prevents splashing, but it also traps sediment and mineral buildup. If only one or two faucets have low pressure while others are fine, a clogged aerator is the most likely cause.

Unscrew the aerator by hand (turn counterclockwise) or use a wrench if it's stuck. Rinse it under running water and use an old toothbrush to scrub away white or brown deposits. If it's heavily corroded or damaged, replace it with a new one from any hardware store for $3 to $8. Screw it back on and test the pressure.

If cleaning the aerator doesn't help, the problem is in the supply line to that faucet, not the faucet itself.

Test and Replace Your Pressure Regulator

A water pressure regulator is a bell-shaped device on the main water line, usually near the shut-off valve. It keeps incoming pressure from the street (which can be 80 to 100 pounds per square inch) at a safe level for your home's pipes (typically 40 to 60 psi). When a regulator fails, pressure drops gradually.

You can test your pressure with a cheap gauge from any hardware store. Screw it onto an outdoor faucet and turn the water on. Normal pressure is 40 to 60 psi. If you're below 40 psi and your shut-off valve is fully open, the regulator may be failing. A plumber can replace it for $150 to $300, depending on your location and the regulator type.

Some homes don't have a regulator at all — if you can't find one on your main line, your water company may be supplying pressure directly. In that case, contact them to report low pressure; the problem may be on their side of the meter.

Look for Leaks in Your Water Line

A leak in the buried water line between the street and your house reduces pressure throughout the home. You won't see the leak, but you'll notice soft or soggy patches in your yard, a spike in your water bill, or both. The water company owns the line from the street to your meter; you own everything after the meter.

If the problem is on your side, a plumber can locate the leak with acoustic equipment and repair it by digging up and replacing the damaged section. This is expensive — $1,500 to $4,000 or more — but necessary to stop water loss. If the leak is on the water company's side, they will repair it at no cost to you.

Call your water company first to report low pressure and ask them to check their line. They can often tell you within a day whether the problem is theirs or yours.

Consider Your Pipes and Water Demand

Older homes with galvanized steel pipes often develop internal corrosion that narrows the pipe opening. This reduces pressure throughout the house and cannot be fixed without replacing the pipes — a major renovation. If your home was built before 1980 and pressure has been declining for years, corroded pipes are a likely cause.

You may also have a pressure problem during peak hours if multiple people are using water at once. Running a shower, washing machine, and dishwasher simultaneously draws more water than your supply line can deliver. This is not a failure — it's a limit of your system's capacity. If this is your only issue, you can stagger water use or install a larger supply line, though the latter is expensive.

When to Call a Plumber

Call a plumber if pressure remains low after you've checked the shut-off valve, cleaned aerators, and flushed the water heater. They can test your system with a pressure gauge, inspect for leaks, and diagnose problems you cannot see — like a failing regulator or corroded pipes inside your walls.

A plumber visit typically costs $100 to $200 for diagnosis. Repairs range from $150 (regulator replacement) to several thousand (water line replacement or pipe repiping). Get a written estimate before work begins.

Frequently Asked Questions

Why is my water pressure low only in the morning?

Your water company may be flushing the main line or performing maintenance early in the morning. This is temporary and usually resolves by mid-morning. If it happens every morning, contact your water company to ask about their schedule. Alternatively, sediment in your pipes may settle overnight and temporarily block flow; running a faucet for a minute clears it.

Can I increase water pressure by adjusting something other than the main valve?

No. The main shut-off valve and the pressure regulator are the only two devices that control incoming pressure. Everything else — aerators, screens, supply lines — either restricts flow or fails, but doesn't increase it. If you want higher pressure than your regulator allows, a plumber can adjust or replace the regulator, though most homes are already set to the maximum safe level.

Is low water pressure a sign of a serious problem?

Not always. A clogged aerator or a partially closed valve is minor and cheap to fix. A failing regulator is more expensive but straightforward. A leak in a buried water line or corroded pipes inside your walls is serious and costly. The only way to know is to check the straightforward things first, then call a plumber if those don't work.

How much does it cost to fix low water pressure?

It depends on the cause. Cleaning an aerator costs nothing. Flushing a water heater costs nothing. A plumber's diagnostic visit is $100 to $200. Regulator replacement is $150 to $300. Repairing a water line leak can be $1,500 to $4,000 or more. Start with the free fixes before paying for a service call.

Will low water pressure damage my pipes?

Low pressure itself does not damage pipes. However, the cause of low pressure might — for example, a leak in a buried line will eventually erode soil and create a sinkhole. Corroded pipes that cause low pressure are already failing and should be replaced to prevent leaks. Have a plumber inspect if pressure has been declining for months.