tile fell off, does it damage concrete

Need help.. here is some background first...
my pool is concrete with 1" tile all over. Yes is completely cover with tile.
some of the tile has come off on the border and the concrete is exposed.
I am wondering if water will damage the concrete if I do not replace this right away. I bought this house with the pool so, last year we used the pool with the tile being like this broken. Little by little the tile keeps coming off obviously because water is getting on back of the tile.
the question is : will the water damage the concrete if I do not replace this right away.??
I do not have the cash to replace this tile now. so I want to wait till next year..
TIA.

here a pic of my pool, if you look at the edge you can see some area that are gray that is the concrete.. I will try to take a better pic of the area to post. this is the only pic I have right now..



http://im1.shutterfly.com/procserv/4...6108IZMmjdq0cc

If you do not take care of the missing tile now then next year you may be tiling the entire pool and that will cost a lot more than water line tile this year. Also check to see if your caulk joint between the coping and pool deck is still good. If the caulk is missing or cracked then this could be the cause of the water line tile problem.

I would suggest you lower your water until it isn't above any missing tiles. As imfignewton said once you get one off you can get water behind the others near it and that will loosen those tiles and it will be a cascading effect. Typically you see this when a pool is really full and water gets behind the top tiles loosening them and eventually popping them out.

It won't however hurt the concrete in any way, just loosen more of the tiles near the exposed area. If you can't or aren't going to replace the tiles use a silicone to seal the edges of the tiles that are exposed to stop the water from getting behind the tiles.