Why Is My Water Bill So High?

By the Plumbing Pros Sherman TX team Published March 4, 2026 · Updated August 22, 2026

The usual suspects, from most to least common

Toilets are the quiet champions of water waste. A worn flapper or a fill valve that will not fully shut lets water trickle from the tank to the bowl continuously, often with no sound and no visible overflow, and a single running toilet can add thousands of gallons to a bill over a month. Because it is both the most common cause and one of the cheapest to fix, the toilet is always the first place to look. A simple check is to put a few drops of food coloring in the tank and see if color appears in the bowl without flushing.

After toilets come dripping faucets and fixtures, which waste less per minute but add up over time, and then the leaks you genuinely cannot see: an underground irrigation line, the service line running to the house, or a leak under the slab. Each of these can run continuously without ever showing at the surface, which is exactly why a bill can climb while everything inside the house looks and sounds normal.

The meter test, and what it tells you

Your water meter is the most useful diagnostic tool you own, and it is free. Turn off every water-using fixture and appliance, including the ice maker and any irrigation timer, then read the meter, wait 15 minutes without using any water, and read it again. Movement means water is leaving the system somewhere. Many meters also have a small low-flow indicator, a little dial or triangle that spins on even tiny flows, and if it is turning with everything off, that alone confirms a leak.

The meter test tells you that you have a leak, and roughly how fast, but not where. To narrow it down, you can isolate the house from the yard: if your setup has a shutoff where the line enters the home, close it and watch the meter again. If the meter stops, the leak is between the meter and that valve, meaning the yard or service line. If it keeps running, the leak is inside the house. That single step splits the search in half.

Telling the leaks apart

Once you know whether the leak is inside or outside, the signs get more specific. Inside, a running toilet, a fixture drip, or a warm spot on the floor from a hot-water slab leak are the things to check. Outside, a soft or unusually green patch of grass, a spot in the yard that stays wet, or a drop in pressure can point to a service or irrigation line. On the sandier west and north sides of Sherman these yard leaks tend to surface, while on the clay east and south they may show as foundation movement first, because the clay holds the water.

If the inside checks come up empty and the meter still moves with the toilets confirmed good, the leak is likely hidden in a wall, under the slab, or in the yard line, and that is where professional leak detection earns its keep. Acoustic and pressure equipment can find a leak behind concrete or underground without opening anything exploratory, which is what a slab leak in particular calls for.

Fixing the cause, not just the bill

The good news is that the most common cause is also the cheapest to fix. A running toilet is usually a flapper or fill valve, a small part and a quick toilet repair, and a dripping faucet is often just a worn cartridge. Knocking out those easy wins first frequently solves the mystery bill entirely, and it costs very little to do.

When the cause is a hidden or underground leak, fixing it promptly matters beyond the bill, because a leak under or near the house can eventually reach the foundation or become water damage. Confirming it early with the meter test, narrowing it down with the inside-versus-outside check, and bringing in location equipment only when needed is the sequence that solves it at the lowest cost. A bill that has doubled is the house telling you to run that test today rather than next month.

Leak Detection questions, answered