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July 11, 2026

How to Find a Water Leak in Your House

Start With the Water Meter Test

Make sure nothing in the house is using water, then find your water meter and note the reading. Wait an hour or two without using any water and check it again. If the reading changed, water is moving through the system somewhere, which confirms a leak exists before you go looking for its exact location.

Check the Usual Suspects First

A few fixtures account for most hidden leaks: toilets (drop food coloring in the tank and check if it appears in the bowl without flushing), the water heater and its connections, and the supply lines under sinks. These are quick to check and rule out before assuming the leak is somewhere less accessible.

Look for the Telltale Signs

Walk the house looking for damp or discolored patches on walls, ceilings, or flooring, a musty smell that will not go away, warped or soft flooring, or unusually green or soggy patches in the yard. The sound of running water when everything is off is also worth tracking down room by room.

What to Do If You Can't Find It

Leaks inside walls, under a slab foundation, or in the underground line between the meter and the house are not visible and usually will not be found by inspection alone. These situations typically call for leak detection equipment to pinpoint the source without unnecessary digging or demolition, which is a good point to request a connection with a local provider.

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Frequently asked questions

How long can a hidden leak go unnoticed?
Depending on its size and location, a slow hidden leak can run for weeks or months before it becomes obvious through a bill increase or visible damage, which is why the meter test is worth doing periodically.
Can I use the food coloring toilet test for other leaks?
That test is specific to toilets. For other fixtures, watching for moisture, corrosion, or a drop in water pressure at that fixture is a more useful indicator.
Is a slab leak serious?
Yes, a leak under a concrete foundation can cause significant water damage over time and is generally worth addressing promptly once confirmed. Specialized detection equipment is usually needed to locate it accurately.

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