The waterline tile and the coping on top of it sit right where the pool takes the most abuse: sun on one side, water on the other, and the deck pushing against it every time the clay under it swells or shrinks. So it's no surprise that loose tile and cracked coping are the most common repair calls we get in the DFW area.
Repair is the right answer when the problem is local. A handful of tiles popped in one spot, a single coping stone cracked where a planter was dropped, or grout that's washed out along a few feet. We remove the failed pieces, check the bond beam behind them, reset with proper thinset, regrout, and re-caulk the expansion joint. That's usually a one-day job and it stops water getting behind the rest of the band.
Replacement is the right answer when the cause is structural or the damage has spread. If the bond beam has cracked or shifted, if more than a quarter of the tiles sound hollow when tapped, or if the coping has lifted along a whole side, patching will just move the failure a few feet down the line. In those cases we remove the full band, repair and level the beam, and install new tile and coping so the whole perimeter is sound.
The economics favor acting early. A few loose tiles reset this year is a small invoice. The same tiles left for two winters let water into the beam, and the repair becomes a replacement. If you're not sure which situation you're in, ask for a free estimate; we tap-test the entire band and tell you honestly what it needs.