Over a period of time, the settling of a house results in a crack between the rim of the bathtub and the wall. Cracks may also appear between the sink and the wall or in the shower stall. You can patch these cracks and any cracks between the tiles on the bathroom walls with a tube of waterproof flexible caulking compound.
Fixing the crack between the bathtub and the wall – Clean and dry the area and remove any loose old caulking with a putty knife and then a stiff brush. Cut the spout off the caulking tube sufficiently far back to produce a ribbon of caulking large enough to fill the crack.
Squeeze the tube while moving it forward to force the caulking into the crack and to form an even bead the length of the crack. Let the caulking dry overnight before using the bath.