Many swimming pools and bathrooms have something in common with each other besides being a place where there's water. Bathrooms and swimming pools sometimes actually have the same kind of ceramic tiles applied to their surfaces, but they have to be the right type. "Ceramic tile" is the general name given to a large class of specific ceramic tile types, including glazed porcelain ceramic tile. Basically, bathroom ceramic tiles for use in swimming pools need to be floor-grade in quality and nonporous.
Ceramic tiles themselves are a very broad class, with many being too soft and not acceptable for use in bathrooms and swimming pools. Also, a ceramic tile suitable for use in both bathrooms and swimming pools has to be very durable and water resistant. No matter the specific use -- bathroom or swimming pool -- ceramic tiles are basically just pieces of fired clay. Baking certain kinds of ceramic tiles at higher temperatures will make them able to withstand use in pools and bathrooms.
Bathroom ceramic tiles suitable for use in a swimming pool are rated floor-grade in toughness. Also, if a bathroom ceramic tile is used in a swimming pool, it has to have low water absorption ratings. Class 3 bathroom ceramic tile types are suitable for most floor-grade applications. Bathroom and swimming pool ceramic tile also has to be either vitreous (0.5 to 3 percent absorption) or impervious (0.5 percent or lower absorption) to moisture.
If you want to ensure that the bathroom ceramic tile you use in your bathroom can go into your swimming, pool use a glazed porcelain ceramic tile. Porcelain ceramic tiles are just another type of ceramic tile and are extremely durable and water resistant. All porcelain tiles are at least vitreous in terms of water absorption resistance. Glazed porcelain ceramic tiles stand up well to frost and cold temperatures found outdoors, too, though they tend to cost more.
Ceramic tile durability ratings are also known as their Porcelain Enamel Institute (PEI) Ratings. A bathroom or swimming pool's ceramic tile PEI rating is a measure of its abrasion resistance. Ceramic tile water absorption ratings are determined by the American Society for Testing Materials. Only vitreous or impervious ceramic tiles are used in swimming pools. As of June 2011, glazed porcelain swimming pool waterline tile costs about $4 per square foot.