How to find a hidden water leak

Start with the water bill and the meter

A bill that rises without a reason is the first clue. Compare it with the same season last year rather than last month, since summer lawn watering and winter habits both change usage.

Then run a meter test. It takes a little time but needs no tools.

1. Turn off every faucet, and make sure no one is using water. Pause the dishwasher and washing machine, and turn off the ice maker if you can.
2. Find your water meter. In many Ohio homes it is in the basement near where the water line enters, though some are in an outdoor pit near the street.
3. Look at the leak indicator, usually a small triangle or dial. If it is turning, water is flowing somewhere.
4. If there is no indicator, write down the reading, wait an hour or two without using water, and read it again.

A change means there is a leak. Next, find out whether it is inside or outside the house. Close the main shutoff valve and check the meter again. If it still moves with the main closed, the leak is in the line between the meter and the house, which is buried and needs a plumber with the right equipment.

Check toilets and other usual suspects

A leaking toilet can waste a large amount of water without making a sound. The usual cause is a worn flapper at the bottom of the tank that does not seal.

To run a dye test, remove the tank lid and add ten or so drops of food coloring to the tank. Do not flush. Wait fifteen minutes or so. If color shows up in the bowl, the flapper or fill valve is leaking. Replacement parts are common and many homeowners handle this repair. If you are not comfortable, a plumber can do it quickly.

Work through the rest of the house the same way:

• Look under every sink for drips, damp cabinet floors and corrosion on the shutoff valves
• Check the washing machine hoses for bulges, cracks or wetness at the connections
• Look around the base of the water heater and at its fittings and relief valve discharge pipe
• Check outdoor faucets and any irrigation valves, since a stuck valve can leak underground
• Look at the refrigerator and ice maker supply line, which is often a thin tube hidden behind the unit

If the toilet test and every visible fixture are clear and the meter still moves, the leak is hidden.

Stains, smells and sounds

Your senses can find what the meter cannot locate. Watch for:

• Ceiling or wall stains, often brown or yellow, that grow or return after drying
• Paint that bubbles or peels, or drywall that feels soft
• Warped or buckled flooring, and cabinet bases that are swollen
• A musty smell in a room, basement or crawl space
• Mold or mildew in areas with no obvious moisture source
• Warm spots on a floor, which can mean a hot water line leaking under a slab

Listen in a quiet house. Hissing in a wall, dripping with no visible source, or the sound of water running when everything is off should be taken seriously. Put your ear to the wall or use a stethoscope-style listening tool from a hardware store.

Basement dampness needs a second thought in Ohio. Heavy rain and clay soils can push groundwater through foundation walls, and that is a drainage issue, not a pipe failure. If moisture appears only after storms, look at gutters, grading and your sump pump. If it appears in dry weather, a pipe is the more likely cause.

When to call a plumber

Some leaks are well within reach of a homeowner. A loose supply line connection, a worn flapper or a dripping faucet can be fixed with basic tools. Call a plumber when:

• The meter moves and you cannot find the source
• The leak is inside a wall, ceiling or floor, or under a slab
• You suspect a problem in the buried line between the meter and the house
• A pipe is corroded, bulging or has been repaired several times
• You see a stain spreading or mold returning after cleanup
• The water heater tank itself is leaking

Before the plumber arrives, close the shutoff valve nearest the leak, or the main if you cannot find it. If water is near outlets, the electrical panel or appliances, stay away and turn off power at the breaker only if you can reach it without standing in water. Otherwise, call an electrician or the utility.

Plumbers can use acoustic listeners, thermal imaging and pressure testing to find a leak without tearing out more of the wall than needed. Our leak repair page describes how this work usually goes, and you can reach us through the contact page.

Keeping small leaks from coming back

Replace old rubber washing machine hoses with braided stainless ones, and do not leave the machine running while you are away. Swap out stiff, corroded shutoff valves before they fail. Note where your main shutoff is, and test it once a year.

Keep an eye on the meter. A quick check on a quiet evening, once or twice a year, can catch a small problem before it becomes a big one. Pay attention to older homes in particular, where aging galvanized or copper lines may start leaking at several points over time. If that is happening, a plumber can tell you whether repiping a section makes more sense than repeated repairs.

Frequently asked questions

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