Pool leaking 12 cm (5 inches) per day?

[Chomdo]

Hi,

My small concrete pool (2x3m) was constructed just 6 months ago and in the very beginning the water level went down about 1 cm per day. We got into a fight with the irresponsible pool company because of the leak and other issues so we just let it be at first. After a few months use the pool started leaking at a rate of 4 cm per day. We always saw water outside of the pool light area so we were pretty sure the problem was there. Now the pool has been empty for about a month and we got a plumber to seal the pool lighting are better.

So yesterday I filled the pool and now the water level had gone down 5 cm in 10 hours that would be 12 cm per day. I have no idea what’s going on but that's about 500 liters of water flowing out of somewhere in one day (my pool 120cm deep and 5 cubic meters).

Of course I now have to hire another pool company to find out where the leak is. I'm just worried that if it's for example one of the main pipes under the concrete structure then the job would be big and expensive.

Any ideas on cases like this? What could be causing a leak of this scale? There is no visible leakage anywhere either so that 500 liters must be going somewhere under ground.

 

[needsajet]

Does it get down to a certain point and then stop leaking?

Does it have a main drain (round grill at deepest point in the pool) and a skimmer (opening at top of water level that collects leaves, bugs and dust)?

 

[Chomdo]

Does it get down to a certain point and then stop leaking?

Does it have a main drain (round grill at deepest point in the pool) and a skimmer (opening at top of water level that collects leaves, bugs and dust)?

Actually after checking the 24 hour leakage rate I lowered the water level below the skimmer, lighting, return (one of the two) and jacuzzi heads. Now it's been about 4 hours and the water level has gone down only 0,5 cm so significantly less than before. So it seems that it's still going down slightly but hopefully the main problem is at the top part of the pool. Only the main drain, jacuzzi suction and the other return are still below water.

 

[needsajet]

If possible, let it keep dropping until it stops. 5 mil in 4 hours still seems like a leak. Keep any exposed plaster misted and cool (wet) so it doesn't crack.

Have a read through these links and see if anything jumps out at you...
Pool School - Leak Detection
Pool School - Suction Side Air Leaks

- - - Updated - - -

I would definitely also try to keep the builder involved and wanting to solve it.

 

[Chomdo]

If possible, let it keep dropping until it stops. 5 mil in 4 hours still seems like a leak. Keep any exposed plaster misted and cool (wet) so it doesn't crack.

Have a read through these links and see if anything jumps out at you...
Pool School - Leak Detection
Pool School - Suction Side Air Leaks

- - - Updated - - -

I would definitely also try to keep the builder involved and wanting to solve it.

Thanks for the links. It still has about 70 cm to go until empty and of course I can't run the pump now. I could keep it dropping but here in the tropics the water will go really bad so I might not want to keep water there for the next week or two. Will probably have a pool company to come look at it very soon.

What did you mean by keeping "plaster" wet? The pool has been empty and dry for the past month waiting to be fixed.

Unfortunately we can not involve the builder anymore since we run into a lot of trouble with them and were forced to not pay the last 30 % of the constructing cost.

 

[needsajet]

Is it a concrete pool with a coloured coating on it? Plaster is just the common name for a cement mixture, often coloured and/or with various coloured beads in it, applied to the concrete to make it smoother. If you could add a signature, you can add your pool description to that. The instructions for doing so are included in the link 'read before posting' linked in my signature.

If it's been empty and dry for a long time, then no, you can't really keep it misted I suppose. Glad to hear you've retained funds for completion.

 

[Chomdo]

It's a concrete pool with tiling. I'll add a few basic pictures to clarify.

 

[needsajet]

That looks very inviting and fitted out with plenty of equipment.

So in all the exposed pipe and equipment, can you find any drips of water?

 

[Chomdo]

Thanks! I really like the outcome too except for the fact that it's leaking and wasn't built according to standards (normal in Thailand of course). Now all the pipes and equipment are under a wooden seating deck and the pool is surrounded by a tiled terrace. There are no visible drips anywhere around the piping or equipment. I've also closed the main drain (not the hole but the pipe) and the filter and pumps so kind of seems like the water is running out of one of the 3 pipes that are still below water level (return, main drain or jacuzzi suction). We've called a company to come and check the situation this week so I hope they are professional and can locate and fix the leak.

 

[needsajet]

It should be a matter of pressure testing to find the culprit and go from there. Fingers crossed that it's the main drain which you could live without if need be. I wonder if there's a dirty hydrostatic valve down there. If so, it's one of the easier fixes. Fingers crossed for you mate.

And welcome to TFP! Good to have you here

Thanks for doing up a signature as well.

 

[Chomdo]

Thanks a lot for your help too! One more thing I'm interested in knowing is that if the leak is in the main drain could I not use a temporary cap/plug to block the main drain at the pool floor? Like a kind of a plug that I can just take off when I want to drain the pool or backwash the filter?

You mentioned not having the main drain at all. I've heard about that too but do I then need to get an external pump to empty the pool when needed or can a separate system somehow be added to the main pump for occasional use?

 

[needsajet]

For normal pool operation, including circulation, vacuuming, backwash, etc., you should be able to just draw water from the skimmer.

It's very possible to manage pool water chemistry so that draining is not needed, so yep, you can do without a main drain, and use a cheap or rented submersible pump if ever you need to. If you're running it at spa temperatures (e.g. 35 degrees C and higher) with high bather load, then a handy way to drain it might be needed. My pool has no main drain, so I bought a little submersible on sale for $50. I've used it to remove the water before the pool was finished (because of mosquito larvae), and have also used it a couple of times to aerate for pH increase.

A plug might be a solution if the correct size can be found for a suitable inlet opening under the drain cover. Plugs for all the openings might help for finding the leak.