Thanks for your response. yes maybe i wasn't clear. We are thinking to remove the top tiles in the pool, not the spa. (we can see a little dampness on the stone edge of the pool near the top which has led us to possibly believe-could leak water where the top of the concrete pool meets the marble floor?) yes i agree doesn't make sense unless there were cracks and we have explored plumbing and light fixtures to no avail? As i said the grout had been exposed to the harsh elements here in Greece for 7 years with out water in the pool, is it possible that the grout has become porous or not as effective? This is what my plumber is saying and that it's not the plumbing or lights , Any advice most appreciated everyone, any pool specialists please???

The tile layer on your pool is not the waterproof layer. The tile layer only dresses up the concrete underneath. The grout is the same...it makes no difference to the waterproof nature of your pool. You could knock tiles off your pool under water and your pool should not leak at all. The problem is not your grout...or tiles.

yes that makes sense to me, thats what i have been saying basically to my plumber.......so back to arguing with him i guess.

Because your spa is emptying, I would be suspicious about the valve that controls the water between the pool and spa. The seals within this valve may not be functioning properly. However, even if this is one problem...it may not explain why your pool is leaking. Is the pool filled right to the brim so that the seam of the pool wall and the pool deck is under water?

No the pool is not filled to the brim there is a few cm's gap between the top of the water and the marble floor. Thanks again for all advice all really helpful .

Since there is a space away from that seam I am doubtful that removing the top tiles will uncover the problem. Is the dampness on the marble all along the edge or just in one area? Do you know if any of the buried plumbing is in these areas? ( a broken pipe underground?). Can you tell if the ground in any area around the pool is saturated with water?....or any new little streams downslope from the pool?

By the way....looks beautiful!

Beautiful pool Kimyan! There are too many possibilities of what could be causing the leak(s). You may even have more than one leak. Your next move would be to call a swimming pool leak detection company to perform pressure tests and structural (static) tests in the shell.

Tile and grout are not "waterproof" but can be considered watertight. Make sure the tile is made for underwater and is ideally porcelain and not ceramic. Grout VERY EASILY check cracks as it cures and without much attention and exposed to the sun/elements can crack/break which would allow water in-between the tile and the pool shell.

First, the shell of the pool is not "waterproof" it is "watertight." There is some permeability in the concrete shell. But it will retain water so the loss you describe would not likely be be to lack of waterproofing behind the tile. Builders will typically use waterproofing agents behind tile installations as this waterproofing will significantly cut down on permeability as well as efflorescence which can reveal itself on tile and grout joints as white scale.

If we were building this pool, we would use a waterproofing material over the entire shell before tiling.

Second, depending on what part of the country you are in the shell may be susceptible to freeze/thaw damage which can crack the pool shell and often does so right behind the waterline tile area (top 6").

In terms of discovery:

1. Pressure testing all of the lines to the pool and spa (suction/pressure/vac/waterfeatures/venturi/blower lines). If loss of pressure is indicated, then its just a matter of locating the leak's location by using an electronic listening device or helium detection.

2. Ruling out deteriorated spider gaskets or multiport valves on the filter by checking the backwash line (if any) while the filter is in "filter" mode.

3. If no leaks are indicated on the pressure tests or by examining the backwash line, then the next round of testing would be structural. We would dive the pool and check all penetrations in the shell (skimmer throats, returns, drains, hydrostats, lights, vac lines, cleaner sweeps) and we would also look for suspicious grout joints in the tile. All it takes is a crack in the gunite shell to pull water through cracked grout and eventually empty out your pool.

Check here for more info on detecting your pool leak

Bottom line is that you want an experienced leak detection company who has the proper tools for locating the leaks to find the leaks and fix them. You may have multiple leaks.

Best of luck with finding and fixing your leak!

Notice where the water feature in the top right back ground is in relation to the tops of the lighting chases in the bottom left.........
Not sure if this was brought up or fixed already but, I had a similar problem with a friend's pool and it turned out to be the light chases. May be totally different than your set up but, what would happen is that, every time the upper level water feature would fill, it brought the level of the water just a bit higher than where the light chases were stopped. Therefore water would leak out of the chase ends at a pretty decent rate. Shoved a bunch of polybutylene rubber in the chase ends and it stopped it. It is an older pool but I think any chases were supposed to be higher than the highest water level in the pool and some other things I don't recall at the moment.

The original post is nearly 2 years old and poster has had no activity.

Boomers775 the forums here can be relevant for many at any time when the post was formed or after. Your comment was unnecessary or at least should be directed at houzz if you feel all posts and threads should be automatically deleted after 30 days. This same post could be useful to others at anytime my friend.

@janders. Pointing out old posts is not an uncommon thing here on Houzz and contrary to your suggestion it actually does serve a purpose. Folks often don't notice that a post is old so they take the time time to offer help to an original poster that is long gone. While it might benefit some other reader ( and that's great if it does), I prefer to be aware that a post is old if I did not notice.

Thanks Kivi. And to janderson. Making old posts current by commenting can be annoying to people who are genuinely looking to help only to find that the OP is long gone. If someone has a similar problem to this one, they have had a couple of years to post their own dilemma.

What is unnessary is your rudeness in your response.

I respectfully disagree. I think posters can see the timelines on the posts and comments. If there is a related post to their issue then they should post here or create a new post. By posting here you are alerting others that have had some similar issues or weighed in on an issue that is similar to theirs. In my opinion who cares if they post here. Are you going to take the time to police the comments on houzz offering what you consider to be an expiration date? If so, kudos that is a monumental task, that even houzz does not wish to do. If they did they could have all threads deleted every 30 days. But then people would continue to ask the same questions over and over. You see, if you really think about it that is the beauty of not deleting threads. It would have been far easier for you to not reply and perhaps if someone wanted to communicate with the latest post, let them.

Apologies for any Faux Pas or breaking rules...Kinda new here on Houzz....I was fully aware that the original post was from over a year and a half ago. I also saw that someone posted something a year later on the same subject and didn't think that it would be an issue to post what my experience with a similar issue turned out to be. It was 7 years before water was added to the the pool. Who knows where the op is at in regards to their issue. I may have missed their solution.? In all honesty, I for one have gained plenty of information from various forums that have posts well over a few years old. Once you scan past these kinds of posts regarding things irrelevant to what brought you to the original subject, there's actually a lot to be learned. I wouldn't doubt there are actually areas here on Houzz or other forums where people can discuss things like not liking older posts and such for people interested in that kind of thing.

Beyond. You did not commit any faux pas and you had every right to post your experience. Presuming that you had not noticed the dates of the OP I was just pointing it out for you and others that might come on the thread thinking it was a current dilemma. I too noticed the post in 2015 that went unanswered so checked activity and saw there was none since the OP.

I guess this old thread has its purpose though. For those who don't mind and learn something new and those who get frustrated by being drawn in to a dilemma by someone who has not noticed dates of comments.

Totally understand. I hope my post helps as many as it's frustrated....lol... It is actually a great piece of information . My friend was adding water to his pool for years before finding out the issue. Many pool companies tried and failed at finding the problem and it wasn't until we upgraded to led niche lighting that we uncovered the chases over flowing. Thanks for your helping the others that may need it too. It's all useful information any way you slice it I would imagine.

Glad you could help your friend Beyond. We once had a problem with a leaking pool and had to hire a diver to find out the reason. He found a whole lot of crescent shaped punctures in the liner. Came to find out that our son and his friends had been pole vaulting the pool with the skimmer pole!