A long shot, but does anybody know of a good plumber or builder that maybe able to locate a fresh water leak?

I'm located on the Darkside at Patta Village.

The background is that over a number of months my water consumption has been steadily increasing, at one point it did reduce, however, I recently got back from a 2 week trip to the UK and the consumption has increased a lot, the water pump is now kicking in to maintain the pressure about once every 15 seconds for a second or so, which means the leak is on the pressure (house) side and not the tank / city water side.

I've checked all the usual suspects, toilets, sinks etc. with no signs or tell tale noises of a leak, to the point I'm pretty certain the leak is outside. (losing around 1,200L of water a day, if inside it would be very noticeable)

The issue with this is that there are 2 outside taps for garden hoses, for the pipes to reach those taps they are ran under concrete and tiles, so not accessible or visible and there are no obvious signs of a leak outside.

The way the original builders laid the water piping is not good, as it goes from an underground tank to the pump and directly into the house, with barely a few inches of pipe visible and only one main isolation valve, so there is no way of isolating these outside taps.

To try and avoid having to break up the concrete and tiles to find the leak, ideally I need a company that can acoustically detect leaks, so we can at least try to narrow the search down to a smallish area.

TIA.

Check the toilets again - not in the cistern - check the toilet bowl - there could be a slow stream of water running into the bowl continuously - I've had this and its hardly noticeable unless you really look closely.

I would drain all the cisterns down, then turn off the water to them, then see if the pump is still firing as often as it did before.

Just a suggestion 🙂

Theres an old thread on this avout a guy in Bangkok who covers pattaya -----

ACES Pattaya — local option in Huai Yai. They specifically offer “Plumbing & Leak Diagnostics” and say they trace hidden pipe leaks and underground leaks by isolating sections of the water system rather than simply guessing where to open things up.

English: 099-093-8789
Thai: 064-435-0189
Location: Huai Yai, Bang Lamung.

You mention "underground tank to the pump". Not sure if you have an access area to use a tape measure. Could try shutting off the tank fill pipe, measuring the water in the tank, waiting an hour or two while not using any water in the house and see if the tank level drops.

In my experience unless it is caused by some aggressive roots from a tree the leak is almost never in the pipe running under a concrete slab. It is almost always on a fitting somewhere.

30 minutes ago, CharlieH said:

Check the toilets again - not in the cistern - check the toilet bowl - there could be a slow stream of water running into the bowl continuously - I've had this and its hardly noticeable unless you really look closely.

I would drain all the cisterns down, then turn off the water to them, then see if the pump is still firing as often as it did before.

Just a suggestion 🙂

@CharlieH thanks very much for the suggestion, I should have mentioned in my OP that I'd already tried what you suggest both indivdualy and collectively on all 3 toilets, plus all other inside isolation valves, to no avail.
I've also dug a small channel revealing the water pipe in the little bit of soil close to the front outdoor tap and left it to see if this channel fills with water, which I'd expect it to if the leak was on a fitting close to the water tap, this stays dry.

5 minutes ago, J Branche said:

You mention "underground tank to the pump". Not sure if you have an access area to use a tape measure. Could try shutting off the tank fill pipe, measuring the water in the tank, waiting an hour or two while not using any water in the house and see if the tank level drops.

In my experience unless it is caused by some aggressive roots from a tree the leak is almost never in the pipe running under a concrete slab. It is almost always on a fitting somewhere.

@J Branche Thanks for the reply, I've checked the underground tank and this isn't the source of the leak, this tank fills directly from the city water and it is not directly connected to the pressure side of the water pump, the pump picks suction from this tank only.

If I isolate the water out from the pump to the house, the pump maintains pressure as it should do and there is no connection between the house side and the tank other than through the pump, so the leak is definitely house side of the pump.

I am thinking it could be roots, the channel I've dug by the front tap is riddled with them, my thought pattern is one has damaged a pipe, or a fitting under the concrete is leaking, there will be at least 2, possibly 3 straight fittings and 4 90 degree fittings on the front side alone.

51 minutes ago, CharlieH said:

Check the toilets again - not in the cistern - check the toilet bowl - there could be a slow stream of water running into the bowl continuously - I've had this and its hardly noticeable unless you really look closely.

I would drain all the cisterns down, then turn off the water to them, then see if the pump is still firing as often as it did before.

Just a suggestion 🙂

Theres an old thread on this avout a guy in Bangkok who covers pattaya -----

ACES Pattaya — local option in Huai Yai. They specifically offer “Plumbing & Leak Diagnostics” and say they trace hidden pipe leaks and underground leaks by isolating sections of the water system rather than simply guessing where to open things up.

English: 099-093-8789
Thai: 064-435-0189
Location: Huai Yai, Bang Lamung.

Yes, we had that...tiny piece of grit in the cistern filler valve and you had to look carefully to see the tiny ripples in the toilet bowl......staggering how much water gets used by such a tiny flow.

Edited Sunday at 06:06 AM3 days by MIke B Bad

1 hour ago, MIke B Bad said:

Yes, we had that...tiny piece of grit in the cistern filler valve and you had to look carefully to see the tiny ripples in the toilet bowl......staggering how much water gets used by such a tiny flow.

we had similar slow leak in a toilet causing the water pump to kick in for a second every couple minutes.

the leakage through the toilet(s) is nearly invisible.

put some food coloring in the toilet cistern to find the leak. or shine a strong narrow beam flashlight on the inside of the bowl above the water level at night with all the room lights off.

3 hours ago, NoDisplayName said:

we had similar slow leak in a toilet causing the water pump to kick in for a second every couple minutes.

the leakage through the toilet(s) is nearly invisible.

put some food coloring in the toilet cistern to find the leak. or shine a strong narrow beam flashlight on the inside of the bowl above the water level at night with all the room lights off.

Great detective work......that would never have crossed my mind....

You write 1'200 liters per day.

Really? I hab once a leaking tank, but you write the pump goes on and off constantly.

So I see only one solution. Isolate all pipes going to the different locations (dig out whats possible, also only the few inches).

Start systematically, one by one...

Day No. 1:

Cut off number 1 that you can glue a 90° pipe to it. Then glue a straight pipe enough long to do whatever you might have to do later to connect it to the original pipe again (a upside down "U" as example).

Glue that with an end cap.

If no difference...

Day No. 2:

.....repeat...

One by one, not all together at the same time.

You can buy an acoustic water leak detector on Lazada for as cheap as 600-700 baht. To a Thai "plumber" (if there is such a beast), suggesting acoustically detecting a water leak would be akin to something like rocket science, or complex thermodynamics.

Armed with his 3-piece tool kit, your average Tradesman (cough) doesn't stand a chance of finding your leak.

Yieryi Pipeline Leakage Detector Water Leak Finder High Sensitivity Acoustic Sensor for Home Pipes Car Noise Detection | Lazada Thailand

8 hours ago, Gsxrnz said:

You can buy an acoustic water leak detector on Lazada for as cheap as 600-700 baht. To a Thai "plumber" (if there is such a beast), suggesting acoustically detecting a water leak would be akin to something like rocket science, or complex thermodynamics.

Armed with his 3-piece tool kit, your average Tradesman (cough) doesn't stand a chance of finding your leak.

Yieryi Pipeline Leakage Detector Water Leak Finder High Sensitivity Acoustic Sensor for Home Pipes Car Noise Detection | Lazada Thailand

I purchased one of these from Lazada forget the actual price The box it came in is all in Chinese but written on the device is 'HY929, In the end I did not use it as I isolated the line with the leak which was hardly used and put a tap before it.

On 8/22/2026 at 10:55 PM, Mattd said:

@J Branche Thanks for the reply, I've checked the underground tank and this isn't the source of the leak, this tank fills directly from the city water and it is not directly connected to the pressure side of the water pump, the pump picks suction from this tank only.

If I isolate the water out from the pump to the house, the pump maintains pressure as it should do and there is no connection between the house side and the tank other than through the pump, so the leak is definitely house side of the pump.

I am thinking it could be roots, the channel I've dug by the front tap is riddled with them, my thought pattern is one has damaged a pipe, or a fitting under the concrete is leaking, there will be at least 2, possibly 3 straight fittings and 4 90 degree fittings on the front side alone.

I'm not sure of the tank, but the underground tanks are the worse if possible abandon it!

I had one put in from my apartment! if the tank underground isn't re-enforced by with concrete the earth pressure will get to it, then if it has a crack or leak nearly impossible to get to it. Then if the unit fails they are set up just like a toilet it keeps overflowing and you not a clue.

Majority of the houses from my experience and I live also on the darkside the water lines follow the meter outside, they are laided along your separation walls you noted two spouts is each one located on each side, many times when building the T-joint the line then laid it right through the foundation to the otherside.

You noted cemented, is it completely cemented to the separation wall! I years ago had the same problem water bill! I have on one side dirt area so wife can plan veggie etc.. two huge water tanks in back sitting on a cement slab. I started at the spout slowing looking for soil dampness leading all the way to the tank nothing then at one corner of the slab, I notices a wet spot, it took me two weeks crawling between two tanks hammer, slowing breaking up the cement the more I broke the more water I saw finally I exposed the pipe enough that I could lift it cut and l place another connector. The problem the F jackass who put in the line was too cheap to use grout glue instead though laying the cement slab on top would do the trick.

My bill drop 1000 baht thereafter, to make sure this doesn't happen again from the street, I rerouted the entire system above ground pinned it nearly along wth walls around the house of course the section that goes under the house at that time gave me nightmares what to do if it was pipe under the house foundation.

As noted if cemented get one of those experts that can diagnose leaks. good luck

did you ask the water company to come with listening device to hear the leak underground ?

don't you have several switches for ground floor, 1st floor, outside ?

I know we had an issue with a pool leak and couldn’t figure out from where. At the time there was only 1 place in Bangkok that had the acoustic sonar equipment to check out around the pool. They had great reviews, but we ended up going with a local friend of a friend who dug up in two different areas and luckily found it. I don’t remember the name, but I’d definitely check out for the service in Bangkok. They will travel. Those cheap ones on Lazada or Shopee will not really work. Good luck. These water leaks suck and maybe you’ll get lucky finding someone locally who has the equipment. If so please let us know.

You may not agree with my reply but here it is . As well as myself I have known several friends get the same problem and the only remedy was too take the floor up to find the leak . Once repaired and the floor reinstated , all is good , or is it ? It all depends on the skill of the original plumber installation . Poorly glued pipe fittings will fail eventually . In my case the main well pump that feeds the whole house was clicking in every minute . With so much of the pipe under concrete I decided to re-run all of the pipework to the surface to enable easy leak detection and repairs . Problem sorted and no lifting of flooring in the future . If you locate the leak is it possible to bypass the problem pipe run with surface pipe, thus saving digging up the floor ?

Its one thing finding where the leak might be, but another matter repairing it, and who's to say it won't happen again.? sounds like replacing the pipework is inevitable. Might be cheaper to bite the bullet and re route the pipework above ground

Last year I had a pump that was switching on and off every 30 seconds or so but I couldn't find any leaks, turned out to be a problem with the pump

Repairing Pvc pipes can be awkward , when space is limited it can be nearly impossible to use some of the fittings , luckily slip on fittings with screw on joints are now much more easily available and not expensive

Thanks to all for the replies, much appreciated.

To clarify.

• The house is 2 storey, the city water feed to the tank is OK, I've 100% confirmed there are no leaks on this section

• The water feed from the pump to the house almost immediately disappears underground never to be seen again, all of the water pipes are underground, both externally and internally in the house, basically, apart from the end users, no pipes are visible and it would be impossible to reroute the pipes externally

• Apart from the isolation valves for the city water and discharge side of the pump, there are no other isolation valves external of the house, there are isolation valves internally for the toilets and sinks

• The problem is definitely on the pressure (house) side of the pump, if the discharge isolation valve is closed, the pump maintains pressure as it should, as soon as it is opened the pump kicks until for quite sometime to compensate for the loss of water pressure due to the leak

• All toilets have been isolated, individually and collectively, this doesn't stop the pump from continuing to start every 15 seconds or so.

• Ditto for all sinks (although if the leak was here it would be obvious!)

• There are no visible signs of a water leak, i.e., no dampness in the walls, no seeping water anywhere, which is concerning, as the loss is around 1,500L per day and it is going somewhere!