You need a pressure gauge—a $10 tool that screws onto any outdoor faucet

The fastest way to check your water pressure is to buy a water pressure gauge from any hardware store and screw it onto an outdoor faucet (the kind on the side of your house). Turn the faucet on fully, read the number on the gauge's dial, and turn it off. That number, measured in pounds per square inch (psi), is your water pressure. The whole process takes about two minutes.

Most homes run between 40 and 80 psi. Anything below 40 psi feels weak—showers dribble, washing machines fill slowly. Anything above 80 psi can damage pipes and appliances over time. If your reading falls outside that range, you have a problem worth investigating.

A pressure gauge costs between $8 and $15 at Home Depot, Lowe's, Ace Hardware, or any plumbing supply shop. Some hardware stores will lend you one for free if you ask. Look for a dial gauge labeled for water pressure, not air pressure—they look similar but measure different things.

Key Takeaways

  • A water pressure gauge screws onto an outdoor faucet and gives you a reading in psi within seconds.
  • Normal household water pressure is between 40 and 80 psi; readings outside that range suggest a problem.
  • You should test at the lowest faucet in your house (usually a basement or ground-floor outdoor spigot) to get the most accurate reading.
  • If pressure is too low, the problem is usually a closed valve or a failing pressure regulator; if it is too high, you may need a pressure-reducing valve installed.
  • A single low reading does not always mean your whole system has low pressure—test multiple faucets to confirm.

Where to test and why it matters

Test at an outdoor faucet on the lowest level of your house—usually the basement or ground floor. Water pressure naturally drops as it travels upward through your pipes, so testing upstairs will give you a falsely low reading. If you test on the second floor and get 35 psi, that does not mean your system pressure is low; it means the pressure has already dropped by the time it reaches that height.

Turn off all other water-using appliances before you test. If someone is running the washing machine or taking a shower, the pressure will be lower than normal. Wait a few minutes after everything is off, then attach the gauge and turn the faucet on fully.

Write down your reading and the time of day. Water pressure often varies throughout the day—it is usually higher early in the morning and lower in the evening when more people are using water. If you get a surprising result, test again at a different time to see whether the pressure is consistently off or just temporarily high or low.

What low water pressure usually means

If your gauge reads below 40 psi, the most common cause is a closed shut-off valve. Every house has a main water shut-off valve where the water line enters from the street. This valve is usually in the basement, crawl space, or near the water heater. If someone partially closed it—or if it was never fully opened—your whole house will have weak pressure.

Look for a valve that looks like a gate valve (a wheel handle) or a ball valve (a lever handle). If it is a lever, make sure it points in the same direction as the pipe. If it is a wheel, turn it counterclockwise until it stops. Do not force it. If the valve is stuck or you cannot find it, call a plumber.

The second most common cause is a failing pressure regulator—a device that sits on the main water line and keeps pressure from getting too high. When a regulator fails, it often lets pressure drop. If your shut-off valve is fully open and your pressure is still low, the regulator may be the problem. A plumber can test and replace it, usually for $300 to $500.

What high water pressure usually means

If your gauge reads above 80 psi, your water pressure is too high. This stresses pipes, joints, and appliances—you may notice leaks at connections, or your water heater and washing machine may fail sooner than they should. High pressure is often caused by a faulty pressure regulator that is not reducing pressure the way it should.

Some homes do not have a pressure regulator at all, especially older houses. If your pressure is consistently above 80 psi and you do not have a regulator, a plumber can install one. This usually costs $300 to $600 and will protect your whole system. It is worth doing if your pressure is regularly above 90 psi.

In the meantime, you can reduce stress on your appliances by installing a pressure-reducing valve on the water heater inlet line. This is a smaller, cheaper device ($50 to $150 installed) that protects just that one appliance while you decide whether to install a whole-house regulator.

Testing multiple faucets to find the real problem

If one faucet has low pressure but others do not, the problem is probably in that faucet or the line leading to it, not your whole system. A clogged aerator (the screen at the faucet tip) is the most common cause. Unscrew the aerator, rinse it under running water, and screw it back on. If pressure improves, the aerator was the problem.

If multiple faucets have low pressure but the outdoor faucet reads normal, the problem is probably inside your house—a partially closed valve under a sink, a failing water softener, or a clogged section of pipe. If all faucets read low, including the outdoor one, the problem is your main shut-off valve or pressure regulator.

Test at least two or three faucets before you call a plumber. This information will help them narrow down the problem and may save you a service call.

When to call a plumber

Call a plumber if your pressure is below 40 psi and the main shut-off valve is fully open, or if your pressure is above 90 psi and you do not have a pressure regulator. You should also call if pressure suddenly drops for no obvious reason—this can signal a leak in your main line or a failing water heater.

If you are not sure whether the shut-off valve is fully open, or if you cannot find it, a plumber can locate it and check it for you. This is a quick visit and usually costs $75 to $150. It is cheaper than guessing and potentially damaging your system by forcing a stuck valve.

Frequently Asked Questions

Can I use a tire pressure gauge to check water pressure?

No. Tire gauges measure air pressure and are not accurate for water. You need a water pressure gauge, which is designed to handle liquid and reads in the psi range your home uses (usually 0 to 200 psi). They cost less than $15 and are worth having on hand.

What if my pressure is normal but my water still feels weak?

Low pressure at a single faucet usually means a clogged aerator or a closed valve under that sink. Check the aerator first—unscrew it, rinse it, and reinstall it. If that does not help, look under the sink for a small valve and make sure it is fully open (turned counterclockwise).

Does water pressure change with the seasons?

Yes, slightly. Pressure is often higher in winter when fewer people are using water, and lower in summer when demand is high. If your pressure is borderline (around 80 psi), you may notice it creeping higher in cold months. This is normal and usually not a concern unless it goes above 90 psi.

Is high water pressure dangerous?

Not when ready, but it wears out pipes, joints, and appliances faster than normal pressure does. If your pressure is above 80 psi, a pressure regulator will extend the life of your water heater, washing machine, and pipes. It is preventive maintenance, not an emergency repair.

Why does my pressure drop when I run multiple faucets?

This is normal. When you run the washing machine and take a shower at the same time, the water supply splits between them, so each gets less pressure. If pressure drops to a trickle, your system may be undersized for your household, or there may be a partial blockage in your main line. A plumber can diagnose this.