Porcelain tiles are among the hardest and densest materials on the market today. Since they are frequently used as wall tiles in bathroom and showers, you may have occasion to drill through one. A standard drill bit will not be able to drill through the glaze of the tile or the dense clay body. To help make the job easier, use a diamond-tipped drill bit and some cooling oil.
Make an X over the area you wish to drill with two pieces of masking tape. Use a pencil to mark the spot on the tape where you will be drilling to help guide the first cut.
Lubricate the drill bit with cooling oil and place the bit against the masking tape on the tile. Begin drilling at the lowest speed setting possible. Do not push the drill into the tile or exert force; allow the drill to eat into the tile on its own to avoid damage.
Stop periodically and apply lubricant to the drill bit to keep it cool. If the drill bit turns red or begins to smoke, stop immediately and allow it time to cool down. Apply more lubricant to the bit before continuing.
Put a plastic anchor into the hole in the tile before mounting screws or hardware to avoid damage.