Quick answer
A sudden water-bill spike almost always means water is leaving somewhere it shouldn't, most often a silently running toilet, an irrigation break, or a slab leak under the foundation. You can rule out the easy causes yourself with the water meter and a few checks; persistent or hidden leaks, especially under a slab, need professional leak detection before they damage the foundation.
- A spike with no change in usage almost always means a hidden leak.
- Check toilets first, a silent flapper leak is the most common and wastes a lot of water.
- Use your water meter: shut everything off and watch if it still moves.
- Warm floor spots, low pressure, or running-water sounds point to a slab leak.
- Hidden and under-slab leaks need professional detection before they harm the foundation.
When this question matters
Your water bill jumped and your habits didn't change. That gap is the tell-tale sign of a leak, and the sooner you find it the less it costs, in both water and potential damage. Knowing how to rule out the simple causes yourself, and recognizing the signs that mean 'call a pro,' turns a worrying bill into a solvable problem.
Why slab leaks are a North Texas problem
Collin County sits on expansive clay soil that swells when wet and shrinks when dry, moving with the seasons and after big freezes. That constant movement stresses the water lines running beneath concrete slabs, making slab leaks more common here than in many parts of the country. Because they're hidden under the foundation, they often show up first as a mysterious bill spike rather than a visible puddle.
How it works
Rule out the easy causes first
Start with toilets, a worn flapper can let water trickle from tank to bowl silently, wasting gallons around the clock; a few drops of food coloring in the tank that show up in the bowl without flushing confirms it. Then check irrigation, outdoor spigots, and visible fixtures. Many bill spikes end right here, with a part that costs a few dollars to replace.
Use the meter to confirm a hidden leak
If the obvious checks come up clean, turn off every fixture and appliance that uses water and watch the water meter. If the dial or leak indicator keeps moving with everything off, water is escaping somewhere you can't see, between the meter and the house, in a wall, or under the slab. That's the moment to bring in leak detection rather than keep guessing.
Finding a slab leak
Under-slab leaks announce themselves quietly: a warm spot on the floor (from a hot-water line), unexplained low pressure, the faint sound of running water with everything off, or even a damp area on the slab. Locating one without tearing up the whole floor takes specialized equipment, acoustic and pressure detection, so the repair can be targeted. Catching it early is what keeps a leak from becoming a foundation problem.
What to watch for
If you ignore the spike
A leak doesn't fix itself, it runs every hour of every day, and the bill is the least of it. A hidden or slab leak left alone can rot subfloors, feed mold, and undermine the foundation. The cost of finding and fixing it early is almost always a fraction of the damage from letting it run.
If you guess instead of detect
Tearing into a wall or floor based on a hunch is how a small leak becomes a big repair bill. Professional leak detection pinpoints the source first, so the fix is targeted and the rest of your home stays intact. With slab leaks especially, detection before demolition is what keeps the repair sane.
Why trust Burnside
- Burnside's licensed plumbers handle leak detection, slab leaks, and repairs across Collin County.
- We locate leaks with proper detection so repairs are targeted, not exploratory.
- Flat-rate pricing and 0% financing with approved credit through Wells Fargo.
Reviewed by the Burnside team, serving Collin County since 1958 · Last updated June 25, 2026
Common questions
Why did my water bill suddenly go up? +
If your usage didn't change, a hidden leak is the usual cause, most often a silently running toilet, an irrigation break, or a slab leak. Check toilets and visible fixtures first, then use your water meter: shut everything off and see if it still moves. If it does, you have a hidden leak worth locating.
How do I know if I have a slab leak? +
Common signs are a warm spot on the floor, unexplained low pressure, the sound of running water with everything off, or a damp area on the slab, often alongside a higher water bill. Because they're under the foundation, slab leaks need professional detection to locate without tearing up the floor.
Can a small leak really raise my bill that much? +
Yes. A silently running toilet or a slab leak runs continuously, every hour of the day, so even a modest flow adds up fast over a billing cycle, and the wasted water is the cheapest part of the problem compared to the damage a hidden leak can cause.