A small crack in grouting will let water seep behind bathroom tiles. If you catch cracks in time, you can scrape out existing joints and re-grout. You may have to experiment with grout samples to get a good colour match - aging affects the colour of the grout - even if you use a leftover supply of the original material.
If adjacent tiles are loose, don't expect to secure them by fixing the grout. Grout helps to bind tiles together, but it can't keep them in place. Before you fix the grout, remove any loose tiles and cut off any old adhesive from both the tile and the wall or floor. Leave the exposed area to dry, and then reset the tiles with adhesive and grout the edges.
It is advisable to wear safety goggles when applying grout or sealer. Also, some grouts, sealers or adhesives may irritate your skin and it is recommended that you wear rubber gloves when working with these materials.
