Water pressure and leaks: 4 checks to run at home first

Key takeaways

• Measure incoming pressure before buying replacement taps or showerheads.
• Compare flow with other taps off and running.
• Test toilets for silent leaks.
• Check the meter with all water use stopped.

When the shower runs weak and lukewarm at the same time, or the kitchen tap takes forever to fill a pot, the first instinct is often to start shopping for new fittings. That can be an expensive guess. Low pressure in a house can come from the water arriving from the street or well, from a leak somewhere in the plumbing, or from a tap or showerhead that has worn out. Each cause calls for a different fix, and some of them cost nothing to rule out.

The U.S. Environmental Protection Agency's WaterSense home maintenance guidance makes a useful point: properly maintaining your home is an important part of making sure your fittings and systems perform well, save water, and keep your utility costs down. The four checks in this post follow that idea. They start with the water coming into the house, move to the parts of the house that can waste water or lose pressure, and only then turn to the taps and showerheads themselves. Working in that order keeps you from spending money on a faucet that was never the problem.

You will need very little. A pressure gauge that screws onto an outdoor hose bib is the main tool, along with a few drops of food coloring or a dye tablet. The rest is attention: noticing when water is weak, when it runs without anyone using it, and when the water meter starts to move. Most of the checks take only minutes.

These checks suit an ordinary single-family home or townhouse with a few outdoor spigots and a standard water meter. Apartments may offer fewer places to test, but the same logic applies.

This post covers pressure and leaks inside the home's own plumbing. It does not cover water quality, water heater sizing, or problems outside the property line, which need different tests. If you notice rusty or discolored water, those signs belong in a separate search.

Start with the pressure you are aiming for

Water pressure is measured in psi. For these checks, the number that matters most is the pressure of the water entering your home, before it branches off to faucets, showers, toilets, and appliances. That is called the incoming or service pressure, and it is the one reading you can take at a single outdoor spot.

Under EPA's WaterSense program, water-using fittings operate best when a home's incoming water pressure is between 45 and 60 psi. That range is the target for everything that follows. A reading inside it makes the supply a less likely cause of a weak tap, so the rest of the work can focus on leaks and wear.

Pressure and flow are different things, and it helps to keep them apart. Pressure is the push behind the water. Flow is how much water comes out of an opening in a given time. A shower can have adequate pressure and still feel weak if its showerhead restricts flow. Low pressure felt across the whole house is a different symptom, because it points upstream of the taps, which is why the first checks look at the supply and the house as a whole.

Height matters too. Water has to climb to reach upper floors, so a second-floor bathroom can feel weaker than a kitchen on the ground floor even when the supply is healthy. Keep that in mind when you compare a weak upstairs shower with a strong faucet downstairs. A gauge reading at a spigot near the ground floor tells you about the supply, not about the pressure your upstairs shower receives.

Pressure gauges with a hose-thread fitting are widely sold, and they fit the outdoor hose bibs, also called spigots or hose faucets, that most homes have. You do not need a fancy model. You need one that reads clearly in psi, since the target range is given in psi.

Check 1: Measure pressure at an outdoor spigot

Choose the hose bib closest to where the main water line enters the house. That reading is the closest you can get to the incoming supply without opening the plumbing. If your home has no outdoor hose bib, a utility tap with a threaded end can work in the same way, though a filter or a partly closed valve upstream of that tap can lower the reading.

Before you start, make sure no water is running inside or outside. Turn off the washing machine and dishwasher, close any open taps, and wait for the house to go quiet. A running tap pulls pressure down and gives you a reading that describes that moment, not the supply. Screw the gauge onto the spigot, open the spigot fully, and read the needle. If it bounces, take the steadiest reading you can see rather than the highest one. The number you want is the one the supply holds when nothing else is competing for it. If the gauge shows nothing at all, make sure it is screwed on tightly and the spigot is open all the way. A loose connection can leak at the threads and give you a misleading low number.

Then compare the reading to the target range:

• Inside 45 to 60 psi. The supply is in the target range. Move on to Check 2.
• Much lower than 45 psi. Under EPA's WaterSense program, this may mean you need to find and fix a leak in your home. Do Checks 3 and 4 before replacing any fittings.
• Much higher than 60 psi. You may want a professional to adjust the pressure or install a pressure-reducing valve (PRV) to help maintain it at 60 psi. Professional help is an option here.

Keep in mind what the reading does and does not tell you. A reading in range does not rule out a leak, because a leak may be small, intermittent, or hidden inside a wall. A reading out of range tells you the house has a problem to chase, but not which one. That is why the next checks matter.

Check 2: Watch pressure during busy periods

A reading taken on a quiet afternoon can look fine while the house still feels weak at peak times. A guide on planning a water well from Wellowner explains why this happens. It says a day's use may be concentrated into a period of one to two hours, often with laundry, bathroom, and kitchen use happening in different parts of the house at the same time. It also says the water supply system must be able to meet this type of peak demand.

The guide is written for people planning a water well, but the same idea helps explain what many homeowners feel at busy hours. When several taps run together, they all draw on the same supply, and a system that feels fine for one tap can feel stretched when three things run at once.

To test this, pick a busy time such as a weekday morning. Open the kitchen faucet to a steady stream and watch how strong it stays. Then start the shower and run the washing machine on a fill cycle, and watch the kitchen stream while both run. If you can, compare two times of day. A kitchen stream that holds steady on a Sunday afternoon but sags on a weekday morning points toward peak demand. A leak, by contrast, tends to affect the flow at every hour, so it does not wait for the household to get busy.

If the kitchen stream drops only when other taps run, the trouble shows up at peak demand, and the supply side of the house is the place to look first. If the faucet is weak even when nothing else is running, a leak or a clogged aerator is the more likely cause. The aerator is the small screen at the tip of the faucet, and mineral deposits collecting there are a common reason a single tap seems weak.

Pay attention to temperature as well. If hot water weakens far more than cold water when the washing machine fills, the problem may sit on the hot side, such as the water heater or the lines that feed it. That is a useful lead for the leak search described later.

Check 3: Run a dye test on each toilet

Silent leaks are the ones you cannot see or hear. A toilet tank can leak into the bowl without any sound, and the water simply runs down the drain. EPA's WaterSense program advises checking for silent leaks at least once a year. The test itself needs only food coloring or a dye tablet, a few minutes of hands-on work, and the discipline to leave the toilet alone while it sits.

Illustrative example: Test before replacing a showerhead

A weak upstairs shower prompts a toilet leak check before a showerhead purchase:

1. They make sure nobody will flush the toilet during the test, then lift the tank lid.
2. They add a couple drops of food coloring to the tank. A dye tablet works in place of the drops.
3. They wait 10 minutes without flushing.
4. They look into the bowl. Colored water in the bowl means water is leaking from the tank into the bowl without a flush. If the bowl stays clear, no leak appeared during this test.

In this example, color appears, so they address the toilet leak before reconsidering the showerhead.

Check the result

A white bowl makes a faint tint easier to see, so look at the water against a white background before you decide.

Test every toilet in the house, not only the one nearest the weak shower, because a silent leak in a seldom-used bathroom is easy to miss.

When color appears, the usual suspects are the parts inside the tank that seal the water in, such as the flapper and the valve it covers. Those parts wear with age, and a worn one can let water slip past even when the tank looks full and normal.

Check 4: Read the water meter with everything off

Your water meter can settle questions the other checks leave open. Start by turning off every tap, appliance, and toilet supply in the house, including the ice maker and any outdoor hoses. Find the meter, which is often in a box near the street or in a basement or utility room. Look at the reading and at the leak indicator, which is often a small dial or triangle that turns when water moves through the meter. For help with this check, see how to check a water meter for leaks.

Many meters also have a sweep hand or a small wheel that spins when water flows, and that is usually the easiest sign to see. A flashlight helps when the meter sits in a dim box or a basement corner.

Pick a time when nobody will need water, such as overnight or while everyone is out. Before you start, walk the house and confirm that each tap, the dishwasher, the washing machine, the refrigerator's water line, and the outdoor spigots are off. A single running tap will make the meter move and hide what the test is looking for.

Leave everything off for a while, then compare the meter to what you saw first. If the numbers have changed or the indicator is turning, water is moving through the system even though no tap or appliance is running. That points to a leak somewhere in the pipes, the water heater, or a supply line, and the next job is tracking it down. If the meter has not moved, a constant leak is unlikely, but a leak that runs only when something is used is still possible, so the checks above still matter.

Track down the leak

Once the meter shows that water is leaving the system, the search moves into the house. Leaks tend to hide in predictable places. Look under sinks, where supply lines connect to faucets and the drain trap sits. Check the area around the water heater and the lines that feed it, along with the shutoff valves at toilets and the connections at washing machines. Outside, look at spigots, hose connections, and any irrigation fittings.

Look for damp spots, stains on ceilings or floors, soft or discolored areas, and mineral crust around fittings, which often shows where water has been dripping for some time. Listen in a quiet house for hissing or running water inside the walls. Feel for warm spots on floors, which can point to a hot-water line that is leaking.

Tracing a leak is slow work. A leak indicator that turns gently is easy to miss, and a leak that shows up only as a damp patch behind a wall may take longer to pin down. Work through the spots one at a time, starting with the ones closest to the taps that seemed weak.

When you think you have found the spot, test the idea with the meter. Close the nearest shutoff valve that serves the suspect line, then see whether the meter stops moving. If it stops, the leak is on the far side of that valve, away from the meter. Follow the related guide to find a water leak location with meter checks as you narrow the search.

Before you replace any fittings

If the checks point to a leak, fix it first. A new faucet will not restore pressure lost to a leak in a wall, and a faucet replaced for the wrong reason is money spent on a symptom. Once the supply and leak checks come back clean and a tap still disappoints, replacement becomes a real choice.

Start with the cheaper fixes. Unscrew the aerator at the tip of the weak faucet, rinse out any debris, and screw it back on. Then check the shutoff valve under the sink. A valve that is only partly open can restrict flow to one tap even when the rest of the house has good pressure. If the flow improves, you have solved the problem without buying anything.

When you do replace something, the EPA's WaterSense program offers useful guidance on what to buy. For bathroom sinks, which the program calls lavatories, choose new faucets and aerators that carry the WaterSense label, and find them with the WaterSense Product Search Tool. For kitchen faucets, look for models with a flow rate between 1.5 and 1.8 gallons a minute (5.7 to 6.8 liters a minute). Those figures give you a stated standard to compare against as you shop.

Flow ratings are a useful guide, but they are not the whole story. Some people find a lower-flow faucet gentler to use, while others want a stronger stream for filling pots. If a store has the model on display, run it for a moment before you commit.

Start today

Choose a quiet time today, turn off water use, and take the outdoor pressure reading before deciding what to replace.

Related guides: Dishwasher water use checklist: 6 checks before you buy.

Common questions

Does a normal pressure reading rule out a leak?

No, a leak may be small, intermittent, or hidden inside a wall.

What does color in the toilet bowl mean?

Color appearing without a flush means water is leaking from the tank into the bowl.

Should I replace a weak faucet first?

Check the supply, leaks, aerator, and shutoff valve before choosing a replacement.