The bill is usually the first witness
The most reliable early sign of a hidden leak is not something you see, it is something you pay. A supply line weeping inside a wall or under a slab runs day and night, and the first place it shows up is a water bill that climbs with no change in how much water your household actually used. If your OWASA bill jumps for a month you cannot explain, treat that as evidence, not a billing error, and start looking.
The reason to take it seriously immediately is economics. A hidden leak is cheapest to fix the day it starts and most expensive the day it finally shows itself, because in between it is quietly wicking into a subfloor, keeping a sill plate damp under a crawl space, or saturating the ground under a slab until flooring lifts. Early leak detection is almost always cheaper than the repair a found-late leak forces.
Signs it is time to check for a leak
- A water bill that climbed with no change in your usage.
- The meter's flow indicator moves with every fixture off.
- A patch of yard that stays green or soggy in dry weather.
- A warm spot on a slab floor, hinting at a hot-water slab leak.
- The sound of running water when nothing is turned on.
- A ceiling or wall stain that returns after you paint over it.
The meter test you can do tonight
You can confirm a suspected leak yourself in about an hour with no tools. Turn off every water fixture in the house, inside and out, including the ice maker and any irrigation. Find your water meter (usually near the street) and note the reading or watch the small flow indicator, the little dial or triangle that spins when water moves. Wait an hour without using any water, then check again.
If the meter moved, water is going somewhere with everything off, and that is a leak by definition. To narrow it down, shut off the valve where the main line enters the house and repeat: if the meter now holds still, the leak is between the meter and the house, often the underground supply line or an irrigation line; if it keeps moving, the leak is inside. Either way you now have real evidence to hand a plumber, which makes pinpointing it faster and cheaper.
The quieter clues around the house
Beyond the bill and the meter, houses drop hints. A patch of the yard that stays green or soggy in a dry spell can mark an underground supply leak. A faint musty smell in one room, a warm spot on a slab floor (a hot-water slab leak), the sound of running water when nothing is on, or a spot on a ceiling or wall that keeps coming back after you paint over it are all worth investigating rather than ignoring.
Not every clue is a supply leak. A ceiling stain under a bathroom might be a failing toilet seal rather than a pipe, and a damp crawl space can be groundwater rather than plumbing. That is the value of proper detection: it tells the difference before anyone opens a wall. A warm slab spot in particular points toward a slab leak, which has its own approach.
Why finding it beats guessing at it
The temptation with a hidden leak is to start opening walls where you think it is. That is the expensive way, because you are as likely to be wrong as right and every wrong hole is drywall to patch. Professional detection reverses that: acoustic listening equipment, pressure testing and thermal imaging pinpoint the leak so the repair is one small, correct opening instead of an exploratory demolition.
On soft OWASA water, the good news is that leaks here are usually about age, a bad fitting or physical damage rather than mineral corrosion eating the pipe from inside, so a located leak is often a clean, contained fix. If detection turns up not one leak but a pattern of them in the same aging line, that is the signal the conversation has shifted from repair to repiping, which we would tell you honestly rather than selling you a series of patches.
One more reason to act on a suspected leak quickly: many homeowners insurance policies expect you to address a leak promptly once you are aware of it, and damage from a leak left running for months can be treated differently from a sudden burst. We are not insurance advisors, so check your own policy, but the practical takeaway is the same either way, a leak found and fixed early is cheaper, less damaging, and less likely to turn into a dispute than one you watched climb on the bill and did nothing about.
Questions we get
A surprising amount. A pinhole running constantly can waste hundreds of gallons a month, which is why the bill is often the first sign. Beyond the water cost, the real expense is the structural damage it does out of sight while you are not looking.
Turn off all water in and outside the house, note your meter reading or watch the flow indicator, wait an hour using no water, then check again. If it moved, water is escaping somewhere with everything off, which is a leak. Shutting the house valve and repeating tells you whether it is inside or in the yard line.
Yes, that is the whole point of professional detection. Acoustic equipment, pressure testing and thermal imaging locate the leak precisely so the repair is one small, correct opening rather than opening walls to search.
Soft OWASA water is gentle on pipes, so leaks here are usually age, a bad fitting or physical damage rather than the internal corrosion you would fight in a hard-water region. That often means a located leak is a clean, contained repair.
A stain that keeps returning after you paint over it is worth checking, because it means something is still feeding it. It might be a pipe, a fixture seal or a roof issue. Detection tells you which before you spend money on the wrong fix.
Bill up, but nothing looks wet?
Run the meter test, then call. We will pinpoint it without tearing the house apart.