How to Drill Into Grout
- 1). Mark the location for the hole with a grease marker, which is ideal for making marks on most surfaces. Double-check the location to avoid drilling an unnecessary hole.
- 2). Tape the edges of the tiles with painter's tape around the area of grout where you plan to drill. This will provide a guide for you when you are drilling as well as provide some protection for the edges of the tile.
- 3). Install a masonry bit into the chuck at the end of the drill. Open the chuck using the key if it is a keyed chuck or your hand if it is not. Insert the end of the bit that does not have turns on it into the chuck and tighten the chuck.
- 4). Hold the grip part of the drill with the trigger in your dominant hand. Place your other hand under the front of the drill just behind the chuck to keep the drill steady.
- 5). Place the drill at a 90-degree angle to the spot where plan to drill the hole so the hole will be straight. Pull the trigger and guide the bit into the grout to the desired depth. Back the bit out while it is still turning. Remove the tape.
Source...