The most common signs of a slab leak are an unexplained spike in your water bill, the sound of running water when everything is off, a warm spot on the floor, low water pressure, and unexplained moisture or cracks in the slab. The fastest way to check at home is the meter test: shut off all the water and watch whether the meter keeps moving. If it does, you likely have a hidden leak.
What these checks can and cannot tell you
Meter movement can indicate water use or a possible leak, but it does not prove the leak is under the slab. Running toilets, irrigation, treatment equipment and other fixtures can also use water. Do not force a stuck shutoff valve or adjust electrical equipment. Modern Plumbing works with American Leak Detection for professional leak locating and provides the plumbing repair afterward. American Leak Detection confirms its own locating fee before service.
What is a slab leak?
A slab leak is a leak in one of the water lines that run under, or are embedded in, the concrete slab your home sits on. Because the pipes are buried in or below concrete, the leak stays hidden and can go unnoticed for a long time, wasting water and washing out the soil under your foundation. Many Citrus County homes are built on concrete slabs, so these signs are worth knowing.
The 5 warning signs of a slab leak
Water bill spike
A sudden, unexplained jump in your water bill with no change in how much you use is the classic early sign.
Sound of running water
Hearing water moving through the pipes when every faucet and fixture is off points to a hidden leak.
Warm spot on the floor
If the leak is on a hot water line, you may feel a warm patch on the floor right above it.
Low water pressure
A leak steals water before it reaches your fixtures, so pressure drops throughout the house.
Moisture or cracks in the slab
Damp flooring, warped wood, a mildew smell, or new cracks can mean water is pushing up from below.
The do-it-yourself isolation test
If your home is on a water meter, you can find out whether you have a leak, and roughly where it is, in under an hour:
Turn off all water and check the meter
Shut off every faucet, appliance, ice maker, and irrigation system, then watch your water meter. If it is still moving with everything off, water is escaping somewhere.
Find your main house shut-off valve
Locate the shut-off valve where the water line enters the house. Knowing where it is also lets you stop the water fast if a pipe ever bursts.
Shut off the house valve and recheck the meter
If the meter stops, the leak is inside the house, often a line under the slab. If the meter keeps running, the leak is between the meter and the shut-off valve, which means an outside yard line leak.
Isolate the hot water line
Close the valve at the water heater and watch the meter again. If it stops, the leak is on the hot water line. This also buys you time, because you can stop the leak while keeping cold water running to the house.
On a private well? Watch your pump.
Many Citrus County homes are on a well with no meter to read, so the well pump becomes your indicator. With every fixture off, the system should hold pressure and stay quiet. A hidden leak makes the pump keep replacing the lost water. Watch for:
- A well pump that runs constantly, or a pressure switch that clicks on and off (short-cycles) when no water is being used
- The pump kicking on by itself overnight or while you are away
Before blaming a slab leak, rule out a waterlogged pressure tank or a failing pressure switch, since either one can make a pump cycle on its own. If the tank and switch check out and the pump still won't rest, you likely have a leak in the lines, which can include a slab leak. We can test all three.
Don't wait on a confirmed slab leak. Left alone, it can lead to bigger repairs, such as a burned-out well pump or well equipment, high water bills, higher electric bills, or water heater repairs from the extra use. Catching it early means a smaller, less expensive repair.
$95 plumbing evaluation
$95For a flat $95, a professional plumber checks all of your plumbing fixtures and runs our plumbing evaluations to see whether professional leak detection is needed. If it is, we refer you to American Leak Detection. You can also use the self-check steps above first.
If repairs are needed, we give free estimates on all slab leak repairs, so you know your options before any work begins.
Proudly partnered with American Leak DetectionHow the leak gets pinpointed and repaired
Confirming a leak is one thing. Finding its exact spot under concrete without tearing up the whole floor is another. Modern Plumbing works with American Leak Detection and performs the plumbing repairs once the leak has been located. Our partners at American Leak Detection use professional electronic equipment to pinpoint and mark the leak, and then we repair it the least invasive way possible, whether that is a spot repair, a reroute, or a section of repipe. See our slab leak repair page for details.
Slabs, soil, and Citrus County
A large share of Citrus County homes sit on concrete slabs, and our sandy, karst-influenced ground can shift around a leak that runs for a long time. Catching a slab leak early here isn't just about the water bill. It's about protecting your foundation. We have been repairing leaks across Inverness, Crystal River, Homosassa, and Lecanto since 1978.
Why homeowners call Modern Plumbing Services
We have been Citrus County's family plumber since 1978, and three generations of the same family still run the business from our Inverness shop. Our plumbers are not paid on commission, every job comes with an itemized invoice, and we schedule in convenient two-hour windows. We are registered with the Citrus County Building Department and the City of Inverness, and our customer service is award winning, including being named the Citrus County Chronicle Best of the Best Plumber for 2026.
