The EPA puts the average household's leaks at more than 9,300 gallons of water wasted every year, and household leaks nationwide at close to a trillion gallons annually. Nine percent of homes have leaks wasting 50 gallons a day or more. A hidden leak is not a rare event. It is one of the most common things wrong with a house, and most of them are found by accident months after they start.
The signs, ranked by how much they mean
Not every symptom carries the same weight. Some of these are close to proof and some are worth noticing but no more than that. Work down the list.
| What you noticed | How much it means | What it usually turns out to be |
|---|---|---|
| Meter moves with everything off | Close to proof | Something is leaking. This is the test, not a symptom. |
| Warm or hot patch on a tile floor | Strong | A hot-side slab leak. Nothing else heats a floor in a Florida house. |
| Sound of running water with every fixture closed | Strong | A running toilet, or a pressurized line inside a wall or slab. |
| Water bill up with no change in habits | Strong, but check the rate first | Toilet flapper, irrigation, pool autofill, slab leak. Utilities also raise rates, so compare gallons and not dollars. |
| A stain that grows, or comes back after painting | Strong | An active source above or behind it. A stain that stopped growing may be from something already fixed. |
| Musty smell that comes and goes | Moderate | Concealed moisture somewhere. Smell tells you it exists, never where it is. |
| Floor tile lifting, laminate cupping, baseboard swelling | Moderate to strong | Moisture underneath, arriving from below or wicking from a wall. |
| Pressure dropped across the whole house | Moderate | Can be a leak. Can also be a failing pressure regulator or a utility-side issue. |
| Persistent damp spot in the yard | Moderate | Irrigation line, or the service line between the meter and the house. |
One Florida-specific caution before you go further. This state runs at high ambient humidity for most of the year, and condensation produces damp that looks exactly like a leak. Cold water pipes sweat. Air handlers sweat. Toilet tanks sweat and drip onto the floor in a way that convinces people they have a supply leak for months. The meter test is the thing that separates condensation from an actual leak, which is why it comes before everything else.
The two-hour meter test
This is the EPA's own method and it is the highest-value thirty minutes of work available to you. The test does not tell you where the leak is. It tells you whether one exists, and that single fact changes what you do next and how much you should be willing to spend finding out more.
- Turn off every water fixture in the house. Taps, dishwasher, washing machine, ice maker, irrigation controller, pool autofill valve. Tell everyone in the house not to flush.
- Find your meter and photograph the reading. In most Florida subdivisions it is in a rectangular box at the curb just inside the property line, often needing a meter key and often half-swallowed by grass runners that have to be pulled back before the lid will lift. Photograph the whole dial, including the small sweep hand or the little triangular leak indicator if yours has one.
- Wait two hours and use no water at all. Leaving the house makes this easier to enforce.
- Photograph the meter again and compare.
The EPA's standard is unambiguous: if the meter changes at all across a period when no water was used, you probably have a leak. Many meters also carry a small triangle or star that spins whenever water is moving through, and if that is turning with the house closed up, you do not need to wait two hours.
Toilets are the most common hidden leak in a house and by a wide margin the cheapest to fix. Put a few drops of food coloring into each toilet tank and do not flush. If color shows up in the bowl within about ten minutes, that flapper is leaking. The EPA recommends replacing flappers at least every five years regardless. A flapper is a few dollars and about fifteen minutes of work, and it is the single most likely explanation for a bill that went up without anything visible changing.
Narrowing it down without breaking anything
If the meter moved and the toilets are clean, one more free test cuts the search area roughly in half.
Close the whole-house shutoff valve and watch the meter again. In a typical Florida slab-on-grade home the valve is on an exterior wall near the front of the house, often within a few feet of a hose bib, or in the garage near the water heater. With that valve closed, no water should be able to reach any of your plumbing.
- Meter still moving with the house valve closed. The leak is on the utility side, in the service line between the meter and the house. That line runs underground, and it is usually the water utility's responsibility up to the meter and yours after it. Call the utility first, before you call anyone else, because the answer to who owns that pipe determines who pays.
- Meter stops when the house valve closes. The leak is inside your plumbing. Now the question is which part.
From there you can keep narrowing if your house has isolation valves. Close the irrigation zone valve and re-test. Close the pool autofill. Close the valve feeding the water heater and re-test, because a leak that stops when the hot side is isolated is a hot-line leak, which in a slab home is by far the most common kind and also the one that leaves a warm spot on the floor.
Write down what each test showed. A leak detection technician who arrives to a homeowner holding a page of meter photographs and isolation results is working from a much smaller search area, and you are paying for less of his time.
Where leaks hide in a Florida house
Florida construction removes most of the hiding places common elsewhere and concentrates the rest. There is no basement to drip into and usually no crawl space to inspect, so a concealed leak has two directions to go: up through the slab, or sideways inside a wall.
| Where | What fails there | How it shows up |
|---|---|---|
| Under the slab | Supply lines cast into or run beneath the concrete, moving with soil and roots | Warm floor patch, damp tile, widening floor cracks, meter creep |
| Inside wall cavities | Fittings and solder joints behind drywall, shower valve bodies | Stain low on a wall, swollen baseboard, bubbling paint, a soft spot |
| The AC air handler and its drain line | Clogged condensate line, failed pan, disconnected trap | Ceiling stain below the unit, water in the closet, damp along the line route |
| Behind and under appliances | Braided supply hoses, dishwasher and fridge lines, washer valves | Warped cabinet base, dark line along a floor seam, musty cabinet |
| Water heater | Tank corrosion, T&P valve weeping, fittings | Damp around the base, rust at the seam, water in the drain pan |
| The attic | Repiped lines run overhead, condensate lines, AC units placed in the attic | Ceiling stain, insulation matted flat in one spot |
| Irrigation and pool lines | Buried PVC, valve manifolds, autofill valves | A patch of lawn greener or soggier than the rest, meter movement that stops when the zone valve closes |
An air conditioner in Florida pulls a large volume of water out of the air every day, and all of it is supposed to leave through a narrow drain line that clogs with algae. When it backs up, the water goes into the pan and then into whatever is below. It looks like a plumbing leak and it is not one, which matters because the fix is a fifteen-dollar cleanout rather than a plumber. Condensate is unpressurized, appears near the air handler or along the line, and usually stops when the system is off. A supply leak does not care whether the AC is running. See AC drain line water damage.
Slab leaks
A slab leak is a failure in a water line under or inside the concrete your house sits on. In a state where nearly everything residential is slab-on-grade, this is the leak people mean when they say a leak was hidden for a year.
It hides well because the water has nowhere obvious to go. It saturates the fill under the slab, travels along the path of least resistance, and eventually appears somewhere that has no relationship to where the pipe actually broke. A wet spot in the hallway can come from a line under the kitchen. This is precisely why guessing and breaking concrete is such an expensive way to look.
The tell that is close to diagnostic is heat. If a patch of tile is warm underfoot in a room nobody is heating, a hot-water line under that slab is running continuously. Nothing else in a Florida house produces that. Cold-side slab leaks are quieter and usually announce themselves through the meter, damp flooring, or a foundation that starts moving.
Repair is not one decision. A plumber can break the slab and repair the failed section, or reroute, which abandons the buried line and runs a new one overhead through walls and the attic. Reroute is often cheaper and less destructive than it sounds, and on older pipe it also avoids repairing one spot on a line that is failing everywhere. Ask for both options priced separately, and ask specifically what the plumber's opinion is of the remaining life of the rest of that line.
Who to call, and in what order
Three different trades can be involved and they are not interchangeable. Calling them in the wrong order is how people end up paying twice.
- The water utility, if the meter kept moving with your house valve closed. That is their side of the line in most cases, and it is a free phone call before it is anything else.
- A leak detection service or a licensed plumber with detection equipment, to locate the failure. They use acoustic listening gear, line tracing, pressure testing and thermal imaging to find the point without demolition. This is a separate service from the repair and is often priced separately, so ask whether the detection fee is credited against the repair if you use the same company.
- A licensed plumbing contractor, to make the repair. In Florida, plumbing contractors are licensed under Chapter 489 of the Florida Statutes through the Department of Business and Professional Regulation, and you can check any license number yourself on the DBPR site before work starts.
- A restoration contractor, if the leak has been running long enough to soak the structure. This is the one people skip. A plumber fixes the pipe and leaves, and the wet wall cavity stays wet. See how to choose a restoration company.
That last one is the reason a hidden leak is a different problem from a burst pipe. A burst pipe announces itself and gets dried within hours. A concealed leak has been wet for weeks by the time you find it, and the EPA's guidance is that materials staying wet beyond 24 to 48 hours should be assumed to support mold growth. See how long until mold grows. If mold turns up on an area larger than 10 square feet, that is a separate license again: Florida requires a state-licensed mold assessor or remediator under Chapter 468, Part XVI, and a drying company's certification does not cover it.
What detection and repair cost
These are published national market statistics gathered from contractor estimates. They are useful for sanity-checking a number somebody quotes you. They are not a quote for your house.
| What you are paying for | Published range | Source |
|---|---|---|
| Slab leak detection, location only | $280 average, $150 – $400 | Angi 2026 slab leak repair cost data |
| Slab leak repair, all in | $2,280 average, $630 – $4,400 | Angi 2026 slab leak repair cost data |
| Minor slab leak | From about $300 | Angi 2026 slab leak repair cost data |
| Hard-to-reach slab leak | Up to $6,750 | Angi 2026 slab leak repair cost data |
| Reroute instead of breaking slab | $600 – $4,000 | Angi 2026 slab leak repair cost data |
| Pinhole leak repair | $150 – $800 | Angi 2026 slab leak repair cost data |
| Pipe leak repair, general | $250 – $850 | Angi 2026 slab leak repair cost data |
| Drying and restoration, if the structure got wet | Priced separately | See our Florida restoration cost guide |
The shape of that table is the useful part. Finding the leak is a few hundred dollars. Fixing it is a few thousand. Drying out what it soaked is a third number entirely, and it is the one that grows every week the leak goes unfound. That is the whole argument for running the meter test the day you first suspect something rather than the month you finally see a stain.
What not to do
- Do not open walls or lift flooring looking for it. You will be wrong about the location more often than not, and you will have paid for the repair of your own search.
- Do not break slab on a guess. Detection equipment exists precisely so that nobody has to.
- Do not paint over a stain to see if it comes back. It tells you very little and it traps moisture behind a coating.
- Do not assume a stain that stopped growing means the leak stopped. Materials reach saturation and stop spreading visibly while staying just as wet.
- Do not run a dehumidifier and call it handled. Drying the room does not dry a wall cavity being refilled from a live pipe.
- Do not sign anything titled "assignment," "direction to pay," or "work authorization" without reading every line and photographing every page first.
On the insurance side our lane is narrow and we will stay in it. Policies commonly treat a sudden failure differently from long-term seepage, and the distinction can matter a great deal with a leak that ran for months. We are not licensed to tell you how your policy applies or how to present a claim. For general background see does homeowners insurance cover water damage, and confirm anything specific with your own licensed agent. Whatever else you do, keep the meter photographs, the dye test result, and the dates. They are the record of when you knew and what you did about it.
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We are paid a flat referral fee that does not depend on whether you buy anything. FloodReady Florida is not a plumbing or restoration contractor and performs no work.
Common questions
How do I know if I have a hidden water leak?
The most reliable single test is the water meter. Turn off every fixture in the house, photograph the meter, wait two hours without using any water, and photograph it again. The EPA's guidance is that if the meter changes at all over that period, you probably have a leak. Softer signs worth acting on are a water bill that rose without a change in habits, a musty smell that comes and goes, a warm patch on a tile floor, and the sound of running water with everything closed.
What is a slab leak and how do I know if I have one?
A slab leak is a failure in a water line running under or inside the concrete slab your house sits on. Because most Florida homes are slab-on-grade with no basement and no crawl space, a leak there has nowhere to drain and works its way up through the floor. The signs are a patch of floor that is warm underfoot in a room nobody is heating, unexplained damp spots on tile or laminate, floor cracks that widen, the sound of running water with every fixture off, and a meter that creeps. Angi's 2026 data puts slab leak detection at $280 on average, with a range of $150 to $400.
Why is my water bill high with no visible leak?
Most often a toilet flapper. The EPA notes that the average household's leaks account for more than 9,300 gallons of water wasted every year, and a running toilet is the usual culprit because it wastes continuously and silently. Test each toilet by putting a few drops of food coloring in the tank and waiting about 10 minutes without flushing. If color reaches the bowl, that flapper is the leak. After toilets, the common causes are irrigation lines, a pool autofill valve, an outdoor hose bib, and a slab leak.
Can water in my AC closet or ceiling be a plumbing leak?
It can be either, and telling them apart matters because the fix is different. An air conditioner in Florida pulls a large volume of condensate out of the air every day, and when the drain line clogs that water backs up into the air handler pan and then into the ceiling or wall below. Condensate is unpressurized and usually appears near the air handler or along the drain line route, and it typically stops when the system is off. A supply line leak is pressurized and does not care whether the AC is running. Our guide to AC drain line water damage covers the difference in detail.
How much does professional leak detection cost?
Angi's 2026 data puts slab leak detection at an average of $280, in a range of $150 to $400. That buys the location, not the repair. The repair is priced separately and varies enormously with access: Angi puts slab leak repair at $2,280 on average with a range of $630 to $4,400, minor leaks as low as $300, and hard-to-reach leaks up to $6,750. A reroute, which abandons the failed section and runs a new line through walls or the attic instead of breaking the slab, runs $600 to $4,000. These are national market statistics rather than a quote for your house.
Should I look for the leak myself or call someone?
Do the meter test and the toilet dye test yourself. They cost nothing, they take an afternoon, and they answer the only question that matters at this stage, which is whether water is leaving the system at all. Stop there. Do not open walls, lift flooring, or break slab looking for the source. A leak detection technician uses acoustic equipment, pressure testing and thermal imaging to find the point of failure without demolition, and paying a few hundred dollars to avoid guessing is the cheaper path in almost every case.
If a hidden leak has been running for weeks, is the damage already done?
Possibly, and that is the reason not to wait. The EPA's guidance is that materials staying wet for more than 24 to 48 hours should be assumed to support mold growth, and a concealed leak has by definition been wet far longer than that. The practical consequence is that a slow leak found late is usually two jobs rather than one: a plumber to fix the pipe, and a restoration contractor to open, dry and document the affected structure. If mold turns up on an area larger than 10 square feet, Florida requires a licensed mold assessor or remediator under Chapter 468, Part XVI.
Keep reading
- AC drain line water damage. The Florida leak that is not a plumbing leak.
- Burst pipe water damage. When the failure announces itself instead of hiding.
- How long until mold grows. Why a leak found late is a different problem.
- Ceiling water damage. Reading a stain overhead.
- What water damage restoration costs in Florida. The published ranges, with sources.
- All water damage guides
Sources
- U.S. Environmental Protection Agency, WaterSense: Fix a Leak Week. The 9,300 gallon household figure, the nationwide trillion-gallon estimate, the nine percent of homes wasting 50 gallons a day, the two-hour meter test, and the toilet dye test and five-year flapper guidance.
- U.S. Environmental Protection Agency, A Brief Guide to Mold, Moisture and Your Home. The 24 to 48 hour drying window for wet materials.
- Angi, How Much Does Slab Leak Repair Cost? [2026 Data]. Detection and repair ranges, reroute pricing, and slab leak signs.
- The Florida Senate, Florida Statutes Chapter 489. Construction contracting, including plumbing contractor licensure.
- Florida Department of Business and Professional Regulation, DBPR licensee search. Verifying a contractor's license status before work begins.
- Florida Department of Business and Professional Regulation, Mold-Related Services licensing FAQs. The 10-square-foot threshold under Chapter 468, Part XVI, Florida Statutes.
What FloodReady Florida is, and is not. We are a consumer information site. We are not a plumbing contractor, we are not a leak detection company, we are not a water damage restoration contractor, we are not a mold assessor or remediator, we are not an insurance agency, agent, broker, or public adjuster, and we do not perform any work on your home. Nothing here is insurance, legal, or engineering advice.
How we make money. If you ask to be contacted, we pass your details to one independent, appropriately licensed third-party professional serving your ZIP code. We are paid a flat referral fee, fixed in advance, that does not depend on whether you buy anything or on the size of any job. We receive no commission, override, or payment contingent on a sale.
Under Florida law, only a licensed public adjuster or an attorney may act on your behalf to prepare, file, or negotiate an insurance claim. We do none of those things and we cannot tell you how to present a claim. Published cost data, standards and statutes change, so confirm current details with the licensed professional you hire.