What causes low water pressure and how to fix it
Low water pressure usually comes from one of three sources: a problem at the meter or main line (which you cannot fix yourself), a clogged or failing pressure regulator, or mineral buildup inside your pipes and fixtures. The fastest way to know which one you have is to check whether the low pressure affects your whole house or just one room. If it is everywhere, the regulator or main line is the culprit. If it is one sink or shower, the problem is local buildup or a closed valve.
You can raise water pressure yourself if the regulator is adjustable, or by clearing mineral deposits from aerators and showerheads. If the main line or meter is the problem, you will need to call your water company or a licensed plumber. The good news is that most low-pressure problems are fixable without replacing pipes.
Key Takeaways
- Low pressure affecting your whole house usually points to a faulty pressure regulator or a problem at the meter, while pressure affecting one fixture usually means a clogged aerator or closed shutoff valve.
- A pressure regulator is a bell-shaped device on the main water line where it enters your house; if it has an adjustment screw, you can turn it clockwise to raise pressure.
- Mineral buildup in aerators and showerheads can be cleared by unscrewing them, soaking them in white vinegar for two hours, and scrubbing with an old toothbrush.
- If pressure is low only at the meter or main line, or if your regulator has no adjustment screw, you will need to contact your water company or hire a plumber.
- Water pressure should stay between 40 and 80 pounds per square inch (PSI); above 80 PSI can damage appliances and pipes, so do not raise it beyond that range.
Locate and adjust 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 in the basement, crawlspace, or under the kitchen sink. It controls how hard the water pushes through your pipes. If your regulator has an adjustment screw on top or on the side, you can turn it to raise pressure.
Before you adjust anything, buy a water pressure gauge (about $10 at any hardware store) and screw it onto an outdoor faucet or a washing machine inlet to see what your current pressure is. Write down the number. Then locate the adjustment screw on the regulator—it usually has a plastic or metal cap you can unscrew. Turn the screw clockwise a quarter turn, wait a minute, and check the gauge again. Keep adjusting in small increments until you reach 50 to 60 PSI, which is comfortable for most homes. Do not exceed 80 PSI, because higher pressure can crack pipes and damage water heaters and dishwashers.
If your regulator has no adjustment screw, or if adjusting it does not change the pressure, the regulator itself may be failing and will need to be replaced by a plumber. A new regulator typically costs $200 to $400 installed.
Clear mineral buildup from aerators and showerheads
If low pressure affects only one sink, shower, or fixture, the problem is almost always mineral deposits clogging the aerator (the screen at the tip of the faucet) or the showerhead. Hard water leaves behind calcium and magnesium that narrows the opening where water flows through. The fix is straightforward and costs nothing.
Unscrew the aerator or showerhead by turning it counterclockwise by hand—most come off easily, though some may need a wrench if they are stuck. Soak the part in a bowl of white vinegar for two to four hours. Use an old toothbrush to scrub away the white or tan mineral crust, paying special attention to the small holes. Rinse it under running water, screw it back on, and test the pressure. If it is still low, soak it again for longer or use a small pick or needle to clear any remaining deposits from the holes.
For showerheads, you can also drill out stubborn deposits with a small drill bit (1/16 inch) if scrubbing does not work. Wear safety glasses and go slowly so you do not enlarge the holes. If the aerator or showerhead is very old or damaged, replacing it costs $5 to $20 and takes two minutes.
Check for closed shutoff valves
Every fixture in your house should have a shutoff valve underneath or behind it—under the sink, behind the toilet, near the water heater. If pressure is low at only one fixture, check whether its shutoff valve is fully open. A partially closed valve will cut pressure to that fixture alone.
The valve handle should point in the same direction as the pipe (parallel to it). If it points across the pipe (perpendicular), it is closed or partially closed. Turn it to align with the pipe. If the valve is stuck or will not turn, do not force it—it may break. Leave it as is and call a plumber if you need it moved.
Also check the main shutoff valve where the water line enters your house. It should be fully open. If someone has partially closed it, opening it may restore pressure to the whole house. The main valve is usually near the meter or where the line comes through the foundation wall.
When to call a plumber or your water company
Call your water company first if low pressure affects your whole house and adjusting the regulator did not help. They can check whether the problem is at the meter or main line on their side of the property. This service is usually free. They will send someone to test the pressure at the meter and tell you whether the issue is in your house or theirs. If it is theirs, they will fix it at no cost. If it is yours, they will recommend a plumber.
Call a licensed plumber if the pressure regulator has no adjustment screw, if adjusting it did not work, or if you suspect a leak or broken pipe inside the wall. A plumber can also install a new regulator, replace corroded shutoff valves, or flush mineral deposits from the main line if buildup is severe. Expect to pay $150 to $300 for a service call plus the cost of any repairs.
Do not attempt to replace the main shutoff valve or work on the meter yourself. Both are the water company's property, and tampering with them can result in fines or service disconnection.
Understanding water pressure ranges and safety limits
Normal household water pressure ranges from 40 to 80 pounds per square inch (PSI). Below 40 PSI, showers feel weak and filling a bathtub takes a long time. Above 80 PSI, you may hear banging in the pipes (called water hammer), and the extra force can crack pipes, damage seals in appliances, and shorten the life of your water heater.
Most people are comfortable at 50 to 60 PSI. If you raise pressure above 80 PSI to fix a weak shower, you are trading one problem for a bigger one. If a weak shower persists after clearing aerators and adjusting the regulator, the issue is likely at the meter or main line, and a plumber or water company visit is the right next step.
If you have a pressure tank (common in homes with wells), the tank itself may be the problem. Pressure tanks can lose air charge over time, which reduces pressure. A plumber can recharge the tank, usually for $100 to $200. If you have a well system and pressure is low, contact a well service company rather than a general plumber.
Frequently Asked Questions
How do I know if my pressure regulator is broken?
A broken regulator will not respond to adjustment—turning the screw does not change the pressure reading on your gauge. It may also leak water from the drain port (a small nipple on the bottom). If adjusting the screw does not work or the regulator leaks, it needs to be replaced. This is a job for a plumber.
Can low water pressure damage my appliances?
Low pressure will not damage appliances, but it will make them work slowly. Dishwashers and washing machines may not fill properly or may run longer cycles. High pressure (above 80 PSI) is what damages appliances by stressing seals and connections. Keep pressure in the normal range to protect your equipment.
Why is water pressure low only in the morning?
Morning low pressure is usually caused by high demand in your neighborhood—many people are showering and using water at the same time. This is normal and temporary. If pressure stays low all day, the problem is something else. If it happens every morning and bothers you, a plumber can install a pressure tank to store water and maintain steady pressure during peak times.
Should I hire a plumber or call my water company first?
Call your water company first. They can tell you in one phone call whether the problem is on their side of the meter (free to fix) or yours (you pay a plumber). Most water companies offer this check at no charge. Only call a plumber if the water company confirms the problem is in your house.
What is the difference between a pressure regulator and a pressure tank?
A pressure regulator controls how hard water pushes through your pipes and protects them from damage. A pressure tank (used mainly in well systems) stores water and maintains steady pressure when demand is high. Most city water homes have a regulator but no tank. Well homes usually have both.