Where the problem starts: pressure loss in your pipes
Low water pressure usually comes from one of three places: mineral buildup inside your pipes, a partially closed valve, or a problem at the meter or main line. Before you call a plumber, you can check and fix the first two yourself. The third requires your water company or a licensed plumber.
Start by testing whether the problem is everywhere in your house or just one fixture. Turn on the kitchen sink, then a bathroom sink, then a shower. If only one fixture has weak pressure, the clog is local to that line. If the whole house is weak, the issue is in your main line or meter.
Key Takeaways
- Low pressure in one fixture usually means mineral buildup in the aerator or supply line; cleaning or replacing the aerator takes 10 minutes and costs under $5.
- Low pressure everywhere in the house often points to a partially closed shut-off valve at the meter; turning it fully open is free and takes one minute.
- Mineral deposits inside older pipes can only be cleared by a plumber, who may need to replace sections of pipe.
- Your water company can test pressure at the meter for free and will fix problems on their side of the line at no charge.
Clean or replace the aerator on a single weak fixture
The aerator is the small screen at the tip of your faucet. Mineral deposits collect there and restrict flow. Unscrew it by hand (turn counterclockwise) or use a wrench if it is stuck. Soak it in white vinegar for 30 minutes to dissolve mineral buildup, then scrub it with an old toothbrush and rinse it under running water.
Screw it back on and test the pressure. If it is still weak, the aerator is too clogged to clean. Buy a replacement aerator at any hardware store for $2 to $4 — they are universal and take 30 seconds to install. If cleaning the aerator fixes the problem, you have found and solved the issue. If pressure is still low, move to the next step.
Check the shut-off valve at your meter
Your water meter sits in a box, usually in your front yard, basement, or crawl space. Next to it is a shut-off valve — a handle or knob that controls water flow into your house. If someone partially closed this valve, your whole-house pressure drops.
Locate the valve and check its position. If it is a handle, it should point in line with the pipe (parallel, not perpendicular). If it is a round knob, turn it counterclockwise until it stops. Do not force it. Turn the water back on at a faucet and check the pressure. This is the fastest and cheapest fix if it works.
Clear mineral buildup in supply lines
If your house is older than 30 years and has galvanized steel pipes, mineral deposits accumulate inside the pipe walls over time. This narrows the opening and reduces pressure throughout the house. You cannot clear this yourself — a plumber must either flush the line with high-pressure water or replace the affected section.
Before paying for this work, call your water company and ask them to test the pressure at your meter. They do this for free. If the pressure is normal at the meter but weak inside your house, the problem is your pipes. If the pressure is already low at the meter, the problem is on the water company's side and they will fix it at no cost.
Test pressure at the meter yourself
You can buy a water pressure gauge at any hardware store for $10 to $20. Screw it onto an outdoor faucet (the same way you attach a garden hose). Turn the faucet on fully and read the gauge. Normal household pressure is 40 to 60 pounds per square inch (PSI). Anything below 40 PSI is weak.
If your gauge reads below 40 PSI, the problem is in the main line or meter — call your water company. If it reads 40 to 60 PSI but your faucets still feel weak, the problem is inside your house pipes. Write down the PSI number and show it to a plumber; it helps them diagnose the issue faster.
When to call a plumber or your water company
Call your water company first if pressure is low everywhere in the house. They test the meter for free and fix problems on their side of the line at no charge. Ask them to check for leaks in the main line — a slow leak can reduce pressure without obvious signs.
Call a plumber if the water company confirms pressure is normal at the meter but weak inside your house. A plumber can flush your lines, replace a faulty pressure regulator, or replace corroded pipe sections. Get a quote before work starts. Flushing costs $200 to $400. Replacing a section of pipe costs $500 to $2,000 depending on how much pipe needs to come out.
Frequently Asked Questions
Can a water heater cause low pressure?
Yes. If pressure is weak only when you use hot water, the problem is usually a clogged inlet screen on the water heater or mineral buildup inside it. Turn off the water heater, close the inlet valve, and unscrew the inlet line. Clean the screen with vinegar and a brush. If that does not work, the heater may need to be flushed by a plumber.
Does low water pressure mean I have a leak?
Not always, but it can. A slow leak in the main line reduces pressure without obvious wet spots. Your water company can detect leaks during a meter test. If your water bill suddenly jumped and pressure dropped at the same time, a leak is likely.
Will a pressure booster pump fix low pressure?
A pressure booster pump can raise pressure if the source pressure is at least 20 PSI. They cost $300 to $800 installed. Use one only after your water company confirms the meter pressure is stable — a booster will not help if the main line is leaking or the meter valve is partially closed.
Is low pressure dangerous?
Low pressure itself is not dangerous, but it can allow contaminated water to enter your pipes if there is a break in the line. If your water company reports a pressure drop in your area, boil tap water until they say it is safe again.
Why is pressure low only in the morning?
Morning pressure dips happen when many neighbors use water at once and the system cannot keep up. This is normal and temporary. If it happens every morning and lasts more than an hour, call your water company — it may indicate a problem with the local main line.