Although ceramic tiles are virtually maintenance-free under normal circumstances, there are times when a ceramic tile wall requires repairs. For example, the grout in the joints between tiles may start to crumble or fall out or a tile wall may need to be broken into so needed plumbing and electical repairs can be made.

Probably the most frequent problem that crops up with ceramic tile is replacing the grout-cement used to fill in the joints between individual tiles. Once the grout starts to crack or crumble, the quicker repairs are made the less likely the chances are that the damage will spread.

Crumbling or missing grout allows water to get behind the tiles, which hastens the deterioration of the wallboard, lath or other supporting surfaces on which the tiles are mounted. If not repaired in time, the tiles will loosen and eventually fall out.

Prepared grout, usually requiring only the addition of water to make it ready for use, is sold in all hardware stores, home centers and lumberyards. To prepare for regrouting, scrape out as much of the old grout as possible, using the edge of a small cold chisel, an old screwdriver or any similar tool that has a blade thin enough to fit between the tiles.

Work carefully, without twisting or prying, to avoid loosening the tiles, raking the tool along the joint in a straight line. Use a stiff brush to remove all powdery residue and small chips, then dampen the edges of the tile, and the inside of the joint.

Now mix the grout according to the directions on the package and force it into each of the opened joints. If only a few joints are involved, the simplest way to do this is to press the cement into the joint with your fingertip.

If many joints are involved, rub the grout on with a rubber sponge or squeegee taking special pains to press the material into each joint so no bubbles or air pockets are left. Smooth each joint down by rubbing with the handle of an old toothbrush or rounded stick.

Before the cement has a chance to stiffen, remove all the excess from the surface of the tiles by wiping with a damp sponge or by using a squeegee. Finish by polishing the face of a tile with a dry cloth to remove the last of the grout.

If a tile must be replaced because it has been cracked or otherwise damaged, the first thing you should do is scrape out all of the grout around that tile, using the techniques describing above. If the tile is broken or chipped, you may be able to simply pry some of the pieces out.

In most cases, however, you will have to chip the pieces out with a cold chisel and hammer. Start by smashing the tile in or near the center to break it up into smaller pieces. Chip the pieces out with the chisel or by using a stiff putty knife and tapping the handle with a hammer.

After the tile has been removed, scrape off any grout that remains around the edges of the adjoining tiles. Then scrape away the old cement from the wall in back of the tile (assuming there is drywall or similar material behind the tile). If the tile was set in cement on top of wood or wire lath, scrape out the loose cement and any lumps that will interfere with setting the new tile back into position.

Tile cement, which comes ready mixed, is the easiest material to use for installing the replacement tile. Apply a layer to the back of the tile by buttering it on with a putty knife. Keep the cement about half an inch away from the edges to minimize the likelihood of it oozing out around the edges when pressed into position. Push the tile into place, then pound it lightly with your fist or with a block of wood and hammer to seat it properly and to bring it down flush with the surrounding tiles.

If necessary, wedge short pieces of wooden matchstick or pieces of toothpick around the edge to keep the spacing uniform and to keep the tile from slipping while the cement is setting. If any of the cement should ooze into the joints, scrape it out while still soft by using a toothpick or similar implement.

After the cement has hardened, the joints around the tile can be filled with grout, following the precedure outlined above. This should not be done, however, until the cement used to install the tile has been allowed to cure completely.

Sometimes a tile has to be cut to fit, or a piece has to be cut out so the tile will fit around a pipe or plumbing fixture. When a straight cut is needed, the simplest method is to use a glass cutter. Using a metal straightedge as a guide, score the face of the time (the glazed surface) with a single stroke of the glass cutter. Place the scored line directly over a sharp corner or a block of wood and snap the tile in two by pressing down hard on either side of the score mark. Any slight rough edge that remains can then be smoothed with a file.

One common repair problem that crops up on ceramic tile walls is the need for replacing a broken soap dish, towel holder or similar ceramic accessory that was set into the wall as part of the original installation. If a piece has broken off while the body of the dish or holder remains firmly stuck in place on the wall, the simplest repair is to reattch the broken part with a clear expoxy adhesive.

Make sure both surfaces are clean and dry, then coat them with the freshly mixed epoxy cement and press the parts together. Use long strips of masking tape to hold the parts in position. (They don't have to be under pressure, they merely have to be held in contact with each other.) and wait at least 24 hours before removing the tape or applying any weight to the repair.

It's possible the piece cannot be repaired in this manner and must be replaced. In that case, follow the same procedure described for replacing a missing tile. However, use tape to hold it in place while the adhesive dries. Just be sure you purchase a new unit that matches the old one in size. If you can't match the color exactly, you may be able to buy a contrasting or blending color that will still look good.