We have had many clients ask us this question and the answer is yes you can drill a hole through your tile. Especially in bathrooms, you often need to drill a hole to allow for plumbing fixtures.
When drilling a hole through tile you need to remember to drill slowly, use water & do not apply pressure. You will need a drill & a diamond or carbide hole saw bit.
The biggest reason for cracking a tile while trying to drill a hole is uneven pressure. When you are drilling you are putting a lot of pressure on & around the area you are drilling & very little on the rest of your tile. A good way to equalize this pressure is by using a piece of 2x4. Cut a hole in one end of the 2x4, just slightly bigger than the size of your hole saw bit.
Start drilling slowly, using even pressure. Let the hole saw bit do the work & not your drill. Putting too much pressure on your drill will only cause cracking in your tile. Just keep enough pressure to keep the bit snugly against the tile allowing the hole saw bit to make the hole. Remember to stop periodically and dip the hole saw bit in water to cool it down.
The most important thing to remember is to drill slowly.