Grout is the material that is applied between tiles. It helps hold the tiles together, covers the gaps between tiles, and prevents moisture from seeping onto the wood underneath. In the case of showers and other tiled walls, you may need to install a soap holder, handle grasp bar or other accessories. Many of these require you to drill holes into the grout to install screws that hold these accessories in place. A steady hand and careful drilling is required when putting holes into fragile surfaces such as tile and grout.
Loosen the bit locking mechanism on the tip of the power drill. Insert the flat end of the carbite drill bit in the opening. Hold the drill bit steady while tightening the bit locking mechanism on the drill. Set the drill RPM to 100 to 200 but no higher.
Carefully mark the spot on the grout where you want to drill with the pencil.
Spray the drill bit with a small amount of water, being careful not to get water on the power drill itself. The water will help keep the bit cool, as too much heat can damage the grout and tiles.
Hold the power drill and place the tip of the drill bit directly over the pencil mark.
Press and hold the drill trigger. Once the bit is spinning gently, begin to push the bit into the grout at the pencil mark.
Continue to apply light pressure to the drill using your other hand to gently push on the back of the drill while using the trigger hand to keep the drill steady.
Have someone hold the spray bottle while you are drilling. Instruct them to spray a small amount of water onto the drill bit while drilling to maintain a cooler bit surface temperature.
Continue applying light pressure until the hole is the desired depth. With the drill still running, slowly pull the bit out straight back. Do not release the drill trigger until the bit is clear from the hole.
Do not drill at an angle. Drill so that the bit is in a straight line going into the grout. Drilling atn an angle can cause the grout or tile to crack or the bit could slip, doing damage to the tiles.
Consider wearing eye protection and a respirator mask to protect against flying grout particles. Do not use "hammer drills," which can cause excessive damage to tiles and grout.