Water droplets on a coral background

Water Absorption Rate (Porcelain Tile)

Originally contributed by • last updated 3/3/2021

Karolina Grabowska

Outside of picking tiles for their appearance, it’s important to select tiles that are intended for the job. Some tiles are harder and more resistant to moisture, making them a great choice for backsplashes and tub surrounds, while others are more permeable and less slippery, making them perfect for a kitchen floor. With a wide range of tiles to meet any requirement, it’s important to keep the water absorption rate in mind when making your purchase.


When talking about porcelain tiles, the water absorption rate refers to a rating system, developed by the The American National Standards Institute, that determines how much moisture a tile’s composition can absorb. To test the tile’s water absorption rate, it is boiled in water and weighed to measure the change from its original dry state. There are four different ratings to indicate how quickly water is absorbed by the material: non-vitreous (7%), semi-vitreous (3-7%), vitreous (.5-3%), impervious (0-.5%). Knowing how much water a tile can take on will help determine which ones can be used for different applications.

What Type Of Tile Should I Choose?

Whether you’re renovating a bathroom or putting down a new kitchen floor, there are plenty of options when it comes to picking the right tiles for your next big project. But before you make your selections, it’s important to consider where you’re putting up your tiles. Keep in mind things like the amount of traffic, the amount of water, and if they’re going to be inside or outside:

  • For exterior applications, select tiles with a very low water absorption rate (as close to an impervious rating as possible), especially in rainy and colder climates. This will not only help sustain the life of the tile overtime and but also keep moisture out of areas it shouldn’t be.
  • Tiles with a low water absorption rate also repel stains better, which makes them a good choice for backsplashes in kitchens and bathrooms. However, these tiles wouldn’t be the right choice for a floor as they can be quite slippery when wet.
  • Unglazed tiles tend to have higher water absorption rates and less slippery surfaces. Although not as hard or scratch resistant as glazed tiles, these unglazed counterparts often make for great flooring in kitchens and hallways.