Mr. Pipe Plumbing, Los Angeles plumbing and sewer specialists

High Water Bill? How to Tell if You Have a Hidden Leak

By Mr. Pipe Plumbing · August 14, 2026

Opened drywall sections exposing drain piping inside the wall cavities during a repair

When the water bill jumps and nothing about the household changed, the money is going somewhere. Usually it is going through a leak you cannot see. The good news: two tests you can run today, with no tools, will tell you a lot about whether a leak exists and roughly where it lives.

The signs a leak is hiding

  • A water bill noticeably higher than the same month last year, with no new habits to explain it.
  • Water stains, bubbling paint, or soft spots on walls, ceilings, or baseboards.
  • A warm patch on a concrete floor, which can mean a hot water line leaking under the slab.
  • A musty smell in one room that cleaning never fixes.
  • The sound of water moving when every fixture is off.
  • A patch of lawn that stays green and soft while the rest dries out.

One sign on its own proves little. Two together are worth taking seriously, and the meter test below is how you check without opening anything.

The water meter test you can run today

  1. Turn off every fixture and appliance that uses water: taps, ice maker, washing machine, irrigation.
  2. Find your water meter. In most Los Angeles homes it sits in a concrete box at the curb or parkway.
  3. Look for the small low-flow indicator on the dial. On most meters it is a little triangle or star-shaped wheel.
  4. Watch it for two minutes. With everything off, it should be perfectly still.
  5. If it moves, note the meter reading, wait thirty minutes without using water, and read it again.

A spinning indicator or a changed reading means water is leaving the system with everything off. That is a leak, somewhere between the meter and your fixtures. If the movement stops when you close the house's main shutoff valve, the leak is inside the house; if it keeps moving, the problem sits in the line between the meter and the house.

The quiet expense: a running toilet

Before suspecting the slab, check the toilets. A flapper that no longer seals lets water trickle from tank to bowl around the clock, silently, and it moves a surprising amount of water. Put a few drops of food coloring in the tank, wait fifteen minutes without flushing, and look at the bowl. Color in the bowl means the flapper leaks. It is one of the cheapest parts in plumbing, and one of the most expensive to ignore.

Why some leaks stay hidden

Water lines run through the places a house keeps out of sight: inside wall cavities, under slab foundations, underground between the meter and the house. A pinhole in a copper line can run for months behind drywall before anything shows on the surface, and by then the water damage is often the bigger repair. That is why a moving meter with no visible water deserves a prompt look rather than a wait-and-see.

How we can help

We assess and repair accessible water leaks, drain leaks, and fixture problems throughout the property. Our goal is to identify the cause of the problem and recommend an appropriate repair based on the plumbing condition, accessibility, and scope of work.

Leak questions, answered.

The things people ask before they call. For anything else, just give us a ring.

Can a running toilet really raise the bill that much?

Yes. A toilet that runs around the clock moves more water than almost anything else in the house, and it does it silently. The dye test described in this guide takes a few minutes and settles the question.

Is a slab leak an emergency?

It depends on what the water is doing. A warm spot on the floor is worth a prompt call. Water visibly spreading, or a meter that will not stop moving with everything off, is worth closing the main shutoff valve while you arrange the visit. Slab leaks rarely improve on their own.

Will you have to open the wall to fix it?

Not always, and never as a first move. We assess the issue, explain our findings, and provide an estimate before any approved work begins. If reaching the leak does mean opening drywall, that is part of what gets explained and approved first.

Let's find where the water is going.

Call now and talk to a licensed plumber. We assess the issue, explain our findings, and provide an estimate before any approved work begins.

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