The four warning signs of a slab leak
The classic Jacksonville slab-leak signs are a warm spot on the floor, a JEA water bill that jumps $30–$100 with no change in your habits, the sound of running water when every fixture is off, and damp carpet or baseboards with no visible source. Any two together means it's time to get the leak located.
A slab leak is a pinhole or split in a water line running under or through your home's concrete foundation. Because the pipe is buried, the water doesn't announce itself — it soaks into the soil and slab for weeks or months before it surfaces. Watch for:
- Warm floor spots. The most reliable sign. A leak on the hot-water line heats the slab above it — pets love to nap there.
- A jumping JEA bill. A pinhole leak can waste thousands of gallons a month. If your bill climbed two cycles in a row with no lifestyle change, suspect the slab.
- Running-water sound with everything off. A faint hiss or rush behind a wall or under the floor when no fixture is on.
- Damp baseboards, buckling floors, or musty smells. Water tracks along the slab edge and shows up at walls and flooring seams far from the actual leak.
Quick self-test: turn off every fixture and appliance that uses water, then watch the dial at your water meter — in most Jacksonville homes it's in a box near the street. If it's still moving, water is leaving the system somewhere, and under the slab is the most common somewhere.
Why slab leaks are a Jacksonville-sized problem
Most Jacksonville homes are built slab-on-grade — the water lines run under or through the concrete foundation — so when a pipe pinholes, the leak is invisible until it has run for months. That construction style, combined with aging copper in the pre-1990 housing stock, makes slab leaks one of the 904's most common big-ticket plumbing failures.
There's no basement and usually no crawl space here: the foundation is a poured slab sitting on Florida soil, with supply lines beneath it. In older neighborhoods like Riverside, Avondale, Springfield, Murray Hill, Ortega and San Marco, those lines are often original copper or galvanized steel that has been corroding for decades. A leak that would drip visibly from a basement ceiling up north instead disappears silently into the ground — quietly spiking your JEA bill and softening the soil under your foundation until it finally shows up as a warm spot or a wet baseboard.
Meter spinning with everything off?
Talk to a licensed Jacksonville plumber about electronic leak detection — upfront quote before anyone touches the slab.
What slab leak detection and repair costs in Jacksonville
Professional slab leak detection runs $150–$450 in the Jacksonville area, and the repair itself runs $1,500–$5,000+ depending on the fix: rerouting the line overhead usually lands at $1,500–$3,500, while opening the slab for a spot repair typically runs $1,500–$3,000 plus flooring restoration.
| Slab leak job | Typical Jacksonville range |
|---|---|
| Electronic / acoustic leak detection | $150–$450 |
| Reroute one line overhead (attic or walls) | $1,500–$3,500 |
| Spot repair through the slab (jackhammer) | $1,500–$3,000 |
| Multiple-line reroute | $3,000–$5,000+ |
| Whole-home repipe (repeat slab leaks) | $4,500–$15,000 |
The detection fee is often credited toward the repair when the same plumber does both — ask when you call. Every repair is quoted upfront, per job, before work starts: the plumber pinpoints the leak, walks you through the options, and you approve a number before anyone opens a floor or an attic.
How the leak gets found without tearing up your floor
Modern slab leak detection is electronic, not exploratory: the plumber pressure-tests the lines to confirm which one is leaking, then uses acoustic listening equipment — and often line tracing or thermal imaging — to pinpoint the leak through the concrete, usually to within about a foot. The old approach of jackhammering on a guess is obsolete.
The process typically takes one to three hours. First the supply lines are isolated and pressure-tested to confirm a leak exists and whether it's on the hot or cold side. Then acoustic sensors listen for the distinct hiss of pressurized water escaping under the slab, while electronic line tracing maps exactly where the pipe runs. On hot-line leaks, a thermal camera can often see the warm plume through the floor. The result is a precise mark on your floor — which is what keeps the repair bill in the ranges above instead of turning into demolition.
Repair options: reroute overhead vs through the slab
There are two ways to fix a slab leak: abandon the leaking line and reroute a new one overhead through the attic and walls, or jackhammer the slab at the marked spot and repair the pipe directly. Reroutes are usually the smarter money in older Jacksonville homes; spot repairs suit a single failure in otherwise healthy pipe.
- Overhead reroute ($1,500–$3,500 per line). The leaking run is capped off and a new PEX or copper line takes the high road through the attic. No broken concrete, no flooring tear-out, and the new pipe is accessible if it ever needs service. In pre-1990 copper that has already pinholed once, this is usually the recommendation — the rest of that line is the same age and headed the same way.
- Through-slab spot repair ($1,500–$3,000). The concrete is opened at the detection mark, the pipe section is repaired, and the slab is patched. It fixes the leak at its exact point and makes sense for newer pipe or a one-off failure — but flooring restoration is on top, and it does nothing for the rest of an aging line.
If this is your second or third slab leak, stop patching: repeat leaks are how failing pipe systems announce themselves, and a whole-home repipe at $4,500–$15,000 is often cheaper than three separate slab repairs plus three rounds of flooring.
Will homeowners insurance cover a slab leak?
Usually partially. Many Florida homeowners policies cover the cost of tearing out and restoring the slab and flooring to reach the leak, plus resulting water damage — but not the repair of the pipe itself, which is treated as wear and tear. Coverage varies by policy, so read yours and document everything before repairs begin.
That distinction surprises people: the $1,500 of concrete and flooring work may be claimable while the pipe fix itself is out of pocket. Older homes with galvanized or polybutylene pipe can also face exclusions or non-renewal pressure from insurers. Practical moves: photograph the meter reading, the wet areas and the detection report; keep the plumber's written diagnosis; and call your carrier before demolition starts, not after. A licensed plumber's leak-detection report is exactly the documentation an adjuster wants to see.
How 904 Plumbers handles a slab leak call
- You call, we answer. Describe what you're seeing — the warm spot, the bill jump, the meter test result. We'll tell you how urgent it is and what to shut off in the meantime.
- We match you with a licensed plumber. Your job routes to a licensed, insured Florida plumber near you who carries electronic leak-detection equipment and does slab work every week.
- Upfront quote, then work. The plumber pinpoints the leak, lays out reroute vs spot-repair with real numbers, and you approve the price before any work begins.
904 Plumbers is a local referral and dispatch service — the work itself is performed by independent, licensed and insured Florida plumbing contractors, and your assigned plumber's license number appears on your quote and invoice.