A City of Longmont water bill that climbs with no visible leak is one of the most common reasons people call us — and it makes sense, since the leaks that drive bills up the most are usually invisible ones. A slab leak stays under the floor. A silently leaking toilet flapper runs into the bowl and down the drain unnoticed. Your water meter cannot be fooled the same way: it registers every gallon passing through whether or not you can see where that water went, making it the fastest, cheapest diagnostic step before we ever send a truck.
Turn off every fixture and appliance that uses water, including anything on an automatic cycle like an irrigation timer. Find your meter, note the reading, wait at least two hours without using any water, then read it again. Any movement means water left the system somewhere between the meter and your fixtures, even with everything off.
What the Meter Tells Us Before We Arrive
A fast, steady flow points toward a supply-side leak — a slab, yard, or service line failure running continuously. A slower or intermittent flow more often points toward a fixture, most commonly a silently leaking toilet flapper, which can waste hundreds of gallons a day without ever overflowing or making a sound. A bill that has been high for several cycles usually means a smaller, slower leak rather than a sudden failure.
Common Causes Behind a High Bill With No Visible Leak
Slab leaks are common in Longmont's older neighborhoods where bentonite expansive clay movement stresses supply lines — see our slab leak detection page. Silent toilet leaks are next most common; food coloring in the tank showing up in the bowl within ten minutes confirms it. Once you have confirmed loss with the meter test, we combine that flow-rate data with acoustic listening and thermal imaging to pinpoint exactly where the water is going, rather than guessing based on the bill alone.
Frequently Asked Questions
My bill has been high for months, not just one cycle. Does that matter?
It usually points to a smaller, slower leak rather than a sudden failure, since a large leak tends to show up dramatically within one cycle. Slow leaks are exactly what the meter test is built to find.
Could this just be a meter reading error?
It happens, but rarely. If your own meter test confirms flow with everything off, that rules out a reading error and confirms real water loss somewhere in your system.
How much water does a running toilet actually waste?
A worn flapper can waste 200 gallons a day or more, silently, enough on its own to visibly move a monthly bill.