While it doesn't hurt to post it here, there might be an even better forum. Check the master list.

This kind of problem seems like it might be very hard to diagnose from afar since many factors are unknown. If the pool was leaking, I'd think you could determine that from the water level. There could be irrigation or pool pipes that could leak. I would get the paver installers looking into it since the problem is already affecting the pavers. They may be able to help diagnose cause.

Condensation means moisture is being generated somewhere :-) Either from the atmosphere (humidity, high dew point) or from moisture under the surface like from damp soil or a water leak. That it does not appear uniformly over the surface of the travertine would tend to indicate it is not an atmospheric source so I would look to an underground issue being the cause.

I agree bringing in your paving contractor is probably the best way to go and simplest, since they need to do some repair/resetting work anyway.

The settling is a bell-ringer for me, especially if it's only in the area where there is noticeable moisture build-up. If it is condensation then what is the magical source of said condensation? While I have seen patios in the Midwest that have inexplicable moisture issues it seems unlikely for you in Arizona.

To echo @Yardvaark, the pool or irrigation lines could have the tiniest leak and be the culprit. Try to schedule the landscape contractor and the pool contractor for a joint appointment. Whatever the issue, both contractors have a vested interest in making sure that any problem is solved.

Good luck and let us know when you get a solution.

Pressure test on the pool lines is a great place to start.

I was joking about the insulated chiller lines since there is no reason you would have such a thing in your yard. An uninsulated pipe of ground temperature water running through the ground is not going to sweat condensation. It's doubtful any line you would have would be capable of sweating enough to cause a problem. It's more likely a leak or something weird going on that we probably couldn't guess.

following

Did you ever get resolution on this? I am having the exact same issue with the same travertine, so I feel your pain. I also live in Phoenix.

Michelle, this is a long shot but we had a somewhat similar problem after our pool was completed. It eventually (after many months of high water bills) turned out that there was a leak in an irrigation pipe. The thin pipe used by the pool contractor's landscape sub was run right next to the pool deck and was likely cracked during construction. It was behind the valve so that it only leaked when that sprinkler zone ran. Just checking the meter did no good. The excess dampness below the crack was dismissed by multiple people as being caused by the slope and clay soil and was termed "normal." The pool builder denied any responsibility for his sub's damage, which was one of several problems caused by that sub. Between the high water bills and the repair cost, we were out about $2K.

We also had pavers settling in several areas due to the landscape sub's failure to adequately compact the soil used to fill in behind a retaining wall. The pavers had to be lifted and additional stone and sand fill put beneath them.

Our pool's auto-fill feature has also made it harder to diagnose multiple small leaks. We've turned it off a few times to monitor the water level, but evaporation amounts can differ from day to day depending on the weather so it's still not always easy to prove a leak just by watching the water level.

Good luck.