How Can I Find the Water Leak Location in an Old-ish House?

How would you all track down a water leak in an house without the ability to shut off water just to the house vs just the yard? The city called my in-laws to say that their water consumption was super-high, but they can’t find any leaks or running toilets, etc. We’ve done the obvious stuff of trying to listen for running water, turning off the toilet valves, and tracing where we thing there’s internal water lines to look for damp drywall — but go ahead and suggest all the other ‘obvious’ things so I know the full list is checked.

Does anyone out there have a gadget or technique that would let us at least determine if its inside or outside the house, or even better to do a bisection search and find the actual leak?

First up- check at the street to see if the meter is running when no known sources of water are running.

You might have to dig away some of the dirt that covers it, but it’s easy enough to see if the dial is moving. If moving, the. Yea, there is a leak somewhere

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Some thoughts.
Look at the water meter. Depending on the type / age, it might show live usage. With everything turned off, look for water flow.
If there is flow, then it’s inside or outside, as you say. Is there an irrigation system? Those are big culprits, though they also leave a lot of evidence. If there is an irrigation system, turn it on and run through the zones, checking each head.
You can pull the cleanout cover (ick) on the sewer line and see if there is water flowing there.
Check inside all of your cabinets that have faucets, water filters, etc…
If all of that is negative, then you may have to call a plumber.


I agree with @cfstaley - sprinklers or irrigation are the most common issues, if present

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Is this in Austin? 1 level or 2+ levels? Type of foundation?

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Wow fast responses, thanks @stepho and @cfstaley . We checked and the meter is indeed turning. I’m waiting for the word back on how fast the meter changes when they compare “everything is off” vs “everything is off except the fully-open bathtub faucet”.

Will find out if there’s irrigation, don’t think so. Given that the house seems dry I’ll message back that they should look all around the yard for damp soil. They did recently plant a tree.

South Austin, they recently moved in, one story, no basement, will find out about foundation.

Plumber said that we may have to call a specialty place to track it down(!) which doesn’t sound cheap. Hoping some member has a crazy doppler-flow viscometrix non-intrusive dynamic syphygmamometer or something, or maybe instead a handy trick involving a stethoscope and a matchstick and the cosine of theta.

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Given that it’s been very dry, an irrigation leak might be a puddle, or it might just be a patch that’s damp. The soil is likely to be very dry at present.

Walk around all areas of every room. If there is a leak in a slab foundation, sometimes it can cause water under hardwoods or carpet. There will be a squish of this happens.

While walking around - also try to note if there are any mysteriously warm spots (walk barefoot or in socks). This indicates a leak in a hot water pipe. Rare, but we did have this once.


Also - try to sense if anything inside the house smells musty. Any part of any room, including under cabinets, around toilets or inside shower enclosures.


Pipes around here are buried so shallow, I’d be surprised if you have an underground leak big enough for the city to notice but not big enough to make an obvious squishy spot.

Maybe a soil moisture meter would come in handy?

I agree with the others, the first thing to do is read the meter for yourself. That’ll tell you how much water you’re looking for.

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One other thought; the guy who did my pre-purchase home inspection used a FLIR camera to look for moisture in the walls (I saw a leak in the shower show up as a cool splotch).


Good point about the hot water - you can binary (ish) search the inside plumbing by turning off the hot water supply. You should have service valves on both sides of the water heater.

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The water supply to the house typically runs from the meter to the closest hose bib. If their new tree is anywhere close to that line, then searching that area is worthwhile. Again, there is likely to be visible moisture in the soil.


Water is themy greatest fear and biggest problem in houses. Hard to find, it travels, so when you do find it, it may be a long way from source. It destroys just about anything it touches if you don’t see it right away. Mold, mildew. Roof leaks included, and same problems.

Can you get history on the water bills? Sudden increases in water are usually visible. If your leak is not visible, it could be an existing issue from purchase of house. Whether that makes a difference is more of a real estate/ legal issue. Ask the city if they sent out any previous notices. That could make a difference.

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Inside the house, toilets are a common culprit. Put a little bit of food dye in the tank of all the toilets make sure you use something that won’t stain) and if they are leaking you should see color in the bowl in about 5 minutes. Outside look for patches of green grass, Check the curb line downstream of the house to see if anything is seeping out at the curb. If there is a french drain check at the outfall for running water. ask the neighbors if they have noticed anything wet spots in their yards. Sometimes pipes from an old unused irrigation system will pick up the water and carry it off to a corner or edge of the property.


The pipes of a previous home in S. Austin actually crossed the property line of our oddly shaped lot, and the tell-tale wet spot was in my neighbors’ yard. A little different situation, but older homes can have some crazy stuff under them and their yards.


It is hard to believe that someone would install an underground irrigation system without a manual valve at the input to turn it off. One of the first things I would do is install a valve for that purpose. I think it is possible that a leak in an underground pipe could leave very little dampness on the surface, because I checked the drainage in a hole where I was going to plant a tree and found that it was not possible to fill it with water. The fractured limestone under the “top soil” at my location seems to allow the water to go straight down. The pipe from the water meter to the house might be deep enough for this to happen. Also be aware that if someone has driven a heavy vehicle over the pipes (or the water meter) it might break a pipe, especially if the soil was wet at the time.

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Y’all, we appreciate this so much. My folks are taking these steps and watching this thread! Thank you for your care and expertise on this topic.

Water leaks are no joke. Having dealt with a few, I’m terribly sensitive to even the remote possibility. And it’s rarely cheap to address. I hope they find the source promptly, and that the fallout is minimal. @kye and @mrflip , I wish your family good luck. :crossed_fingers:


I installed a Flume water meter meter($200). It’s strapped next to the meter and the induction is converted to flowrate and wirelessly transmitted back to your phone/computer. You can set automatic alerts for various usage patterns, quotas, and irregular small continuous flows that would indicate a leak. Over a couple years it has been pretty accurate, catching not quite fully turned knobs dripping and hard water valve blockages. The batteries last about a year(Lithium single use AA). Installing one of those and turning off individual toilets / sections of the home and viewing the activity log would be much more efficient than trotting back and forth to check the meter and plot it yourself.

In Austin and the surrounding aquifer community there are many areas with very thin topsoil but very porous limestone underneath so the soil might never appear damp. A large tree can also crack a pipe and absorb water faster than it can reach the surface but that’s usually a drain pipe.

To find a difficult leak there are pressure generators(think injection mold hydraulic presses) that can add more pressure to the line and measure if it drops or not with everything closed as well as how much pressure was needed to cause the leak. The instruments are very expensive and I imagine they’d charge a lot for it. Sadly, UNT Health Science research just surplused an extremely expensive setup for like $50 today since nobody is manning the usual surplus/equipment sharing due to COVID. You’d also have to be familiar with the pressure tolerances to not cause more damage.

It might be possible to find acoustically, but most of the leak detectors I contacted in Austin for a pool didn’t have advanced enough signal processing for all of the road and construction noise coming through the ground and I ended up having to make a hydrophone myself. It’s difficult to find a plumber who knows how to use an oscilloscope. For a pressurized line it’s more complicated because the tap and feed would need to be sealed and that’d increase cost. Standard acoustics are detecting water turbulence and can miss leaks that happen at joints because the joints are also turbulent.

Ultrasonic devices exist and are a non-invasive option for measuring section by section but I’m not familiar with them in a residential setting. That might be your best bet if other options are exhausted. Some info avail at

Old-ish might use CPVC in places that can become brittle, especially at the joints. I had one home flood because the plumber swapped a brittle CPVC toilet shutoff valve but the pipe was improperly supported inside the wall and also brittle. The wiggling when fixing the exterior valve cause the interior joint a few feet higher inside the wall to break. If it’s brittle in one place, it’s probably brittle nearby having been exposed to similar degrading chemistry. The original plaster walls had been covered in drywall due to asbestos concerns, so that new leak wasn’t discovered for months until it finally broke through the plaster on the second floor and ceiling collapsed.

Technically speaking one can find cracks in copper lines through electrical resistance but would need to know the blueprints to tell the difference between a crack and joint and that’s not something most people have access to.

A few years ago the city added pressure limiting valves. These can get hard water buildup that keeps the valve slightly open but can be cleaned with CLR. The same can happen with the toilet fill valve inner workings when city work elsewhere leaves metal burrs traveling up the line that wedge in the fill valve and act as a seed for lime buildup. When those are slightly open at all times they can resonate and shake other connections loose. Slowly turning on a bath and listening/feeling for a hum or whistle can indicate this. This type of leak can also be sneaky where the combination of resonance and leaking shakes the toilet tank support bolts loose and the increased tank water weight presses past those gaskets to drain down the backside of the toilet and into the floor - only intermittently and before the toilet automatically flushes itself.

Other people have already added good suggestions - that’s all I know Austin-specific that wasn’t covered.

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A couple of additional things.

If you have not already done this you might check the history of complaints and usage at the water utility. It could be that this has happened before and was resolved. It also might be something to take back to the Title company if it appears this was a known problem before they bought the house.

You might also want to check to see if the property is located in the Edwards Aquifer Recharge Zone. You can do that here:
If they are in the recharge zone and in doing everything else that has been suggested in this thread, you believe the leak must be in the yard you may need professional help finding the leak. I have seen 15 thousand gallons of liquid disappear into the ground in five minutes through a buried recharge feature. Good Luck and Keep us posted on the progress. We are cheering for success!

Eric Kaufman