Despite what many believe, the tile and grout in most showers isn't waterproof all on it's own. It's actually protective membranes and sealants that are installed before and after new tile.

Is all grout water proof?

The answer to the question is, surprisingly, no. Tile and grout is not totally waterproof and neither is cement board, backer board, sealers and cement adhesives, they absorb water but do not block penetration.

What type of grout is waterproof?

Waterproof epoxy grout is ideal for showers and bathrooms because of its bonding power. Epoxy grout won't crack, stain, or shrink, making it an ideal solution for wet environments.