Leak Detection
Pinpoint a concealed leak in a wall, a ceiling or the buried supply line, so only the right spot gets opened.
Homeowner guide
Finding a Hidden Water Leak in a Louisville, CO House
Most hidden leaks can be narrowed down with three tests that cost almost nothing. Start at the meter, check the toilets, then look in the places water shows itself first. If those turn up nothing, a plumber can finish the job.
By the Flatirons Express Plumbing team ·
Start with the water meter
Close every faucet, pause the ice maker and washing machine, and make sure the sprinklers are off. Find the meter, which is in the basement for some homes and in a pit near the street for others, and look for the leak indicator, a small triangle or dial that spins when any water flows.
If it moves with everything off, water is escaping. Note the reading, wait an hour without using water, and read it again. A change confirms a leak between the meter and your fixtures.
Find out which side of the house
Shut the main valve inside the house and check the meter again. If it still moves, the leak is on the line between the meter and the valve, usually underground. If it stops, the leak is inside the house.
That one test tells you whether to look in the yard or in the walls, and it tells a plumber where to start. For a buried leak, see water line repair. For leaks in walls, leak detection covers the tools used.
Test the toilets
Add a few drops of food coloring to each tank without flushing. If color shows in the bowl after fifteen minutes, the flapper is leaking. A leaking toilet can waste a lot of water with no sound, and it is the most common hidden leak in a house.
Listen for a faint hiss or a toilet that refills by itself. Replacing a flapper is inexpensive. If the fill valve never shuts off completely, replace that too.
What the meter test tells you
Shut off every fixture, then watch the meter. Use this table to read what you see.
| What you see | What it suggests | Next step |
|---|---|---|
| Meter stands still | No leak at the moment | Retest later if the bill still looks off |
| Meter keeps moving with everything off | A leak somewhere on the property | Close the house main and watch again |
| Meter stops once the house main is closed | The leak is inside the house | Check toilets, fixtures and the water heater |
| Meter keeps moving with the main closed | The leak is on the line between meter and house | Call for leak detection on the service line |
Look where leaks show up
Check under every sink, around the base of toilets, behind the washing machine and around the water heater. Look at the basement ceiling below bathrooms and the kitchen for stains, bubbling paint or warped drywall. A musty smell in a closed room is another clue.
Check outdoor faucets and the area around the foundation. A hose bib that drips inside its wall in winter can leak where you cannot see. Wet soil next to the house with no rain is a warning.
What your bill is telling you
Compare winter and summer bills. A bill that rises in winter, when you are not watering the lawn, points to a leak. Louisville's own figures put an average home's use near 0.4 acre-feet a year, about 130,000 gallons, so a large unexplained jump is worth chasing.
The city offers conservation programs because its supply is limited. If your usage looks high, call the utility to ask whether it can help check for continuous flow.
Reading wall and floor clues
Paint that bubbles, drywall that feels soft, a musty odor in a closet and warped baseboards all point to moisture. Press gently on suspect spots with a flat hand. Cool, damp patches deserve a closer look, and a thermal camera borrowed or hired can show temperature differences behind a surface.
Check cabinets under every sink with a flashlight, along with the base of toilets and the area around the water heater. Slow drips collect where no one looks, and a stained cabinet floor tells a story.
Outside the house
Walk the yard after a dry spell. A patch of unusually green or soggy grass, a low spot that stays wet or a hissing sound near the meter can point to a break in the service line. Look at hose bibs, irrigation valve boxes and the area around the foundation too.
If your irrigation system runs on a timer, shut it down and recheck the meter. A stuck valve can send water into a yard for hours. Fixing that is a sprinkler repair, but it explains a high bill all the same.
Keeping a simple leak log
Write down the meter reading at the same time each evening and again each morning for a few days. If the reading rises overnight when no one uses water, the house is leaking. If it holds still, your bill probably has another cause.
Add notes about anything that changed, such as a new appliance, a guest stay or the start of lawn watering. A short log gives a plumber a head start and keeps a bill dispute from turning into guesswork.
When to call for help
If the meter test shows a leak and the toilets and visible fixtures are fine, the leak is hidden. A plumber can pressure-test sections of pipe, listen with acoustic gear and scan with a thermal camera to pinpoint it without tearing out walls.
If water is already spreading, do not wait. Close the main valve and call the line. If drywall or flooring got wet, ask about water damage restoration as well.
Quick answers
Leak finding questions
Shut off all water and watch the meter's leak indicator. If it moves, water is escaping somewhere.
Close the main valve inside the house. If the meter still moves, the leak is on the buried line.
Look for stains, warm spots or musty smells. A plumber's acoustic and thermal tools can locate it without opening the wall.
Policies differ. Many cover sudden damage, not wear. Check your homeowner policy and your utility's rules.
Services that connect to this topic
Water Line Repair & Replacement
Fix or swap the underground pipe that feeds the house from the meter.
Water Damage Restoration
Dry and rebuild floors, drywall and basements after a leak, a frozen-pipe burst or a sump failure.
Keep reading
Seven reasons a water bill climbs
A sudden jump usually has one of seven causes, from a running toilet to a sprinkler that stuck open.
Stopping a toilet that never stops running
A toilet that never stops running wastes water and money. The fix is usually a flapper, a chain or a fill valve.
Locating and closing the main shutoff
Every household member should know where the main water valve is and how it turns. Here is how to find it and what to do if it is stuck.
Found a leak you cannot trace?
Call and describe the meter test result. A dispatcher can connect you with a local contractor.