How To Find a Hidden Water Leak
Close every fixture and watch the water meter. If it still moves, you have a leak. That single test costs nothing and is more reliable than any symptom.
What to do right now
Do these first. None of them need tools or plumbing knowledge, and they limit what this ends up costing you.
- Close everythingEvery tap, the dishwasher, the washing machine, the ice maker and any irrigation. Nothing in the house should be calling for water.
- Read the meter, wait, read it againNote the reading, wait fifteen minutes with everything still closed, and read it again. Many meters also have a small triangular or star shaped leak indicator that spins on the smallest flow.
- Isolate the house from the yardIf your main shutoff is inside, close it and watch the meter again. If the meter stops, the leak is inside. If it keeps running, the leak is between the meter and the house.
- Photograph everything before you clean upPhotos and a short video of the water, the source and every damaged item. If you claim on insurance this is the evidence, and it cannot be recreated once the area is dry.
Does this need a plumber tonight?
- The meter runs fast with everything closed
- A warm patch on a floor, which suggests a hot line under a slab
- Water appearing with no visible source
- A sudden large jump in the water bill
- A very slow meter creep you have noted and can report
- A stain that has not changed in months
The signs worth taking seriously
A rising bill with no change in habits, a warm spot on a floor, a musty smell in one room, and reduced pressure are the four that most often turn out to be real.
A warm patch on a concrete floor is the classic slab leak signature, because the hot supply line runs under the slab and heats the concrete above it. It is worth reporting precisely, because it locates the leak better than anything else.
Musty smell in a single room usually means water has been in the wall or under the floor long enough for growth. That is a different timescale from a burst pipe and often a larger repair by the time it is found.
- Water bill rising with no change in use
- A warm patch on a floor
- Musty smell confined to one room or cupboard
- Pressure that has dropped noticeably
- Sounds of running water when nothing is on
- Cracks appearing in a slab floor or patio
How leaks are located
By narrowing rather than by guessing. Isolate sections to find which run is losing pressure, then listen acoustically to place it within a few feet, then open only there.
On slab leaks the sequence adds pressure testing the hot and cold sides separately, because knowing which side is losing tells you a great deal before anything is opened.
The point of all of it is to avoid opening the house in the wrong place. Locating properly usually costs less than a single unnecessary opening and its reinstatement.
What leak detection costs
[PLACEHOLDER: PRICING] Pending from the client.
Locating is priced separately from repair because they are different work and either can be the larger of the two.
Questions people ask about this
How much water does a small leak waste?
More than people expect. A continuous drip can run into thousands of gallons a year, which is why the bill is often the first real evidence.
Can I find it myself?
You can confirm one exists with the meter test, and you can often narrow it to inside or outside the house by closing the main. Placing it precisely is where equipment helps.
My meter moves very slowly. Does that matter?
It might be a running toilet rather than a leak, which is worth ruling out first by putting a little food colouring in the cistern and seeing whether it reaches the bowl.
If that is not quite what you have
Not sure how urgent this is?
Describe what you can see and hear. We will tell you whether it needs someone tonight, and what to do in the meantime either way.
Or send it over
Four things and a photo.