It depends upon the material of the bath mat. It comes in a wide range of materials like bamboo fibre, cotton and even rubber. You can put the cotton and bamboo fibre in washing machines but remember never to wash mats with rubber bases in your machines as they will tear and damage. So, it completely depends upon the material of the mat you are using. It is better to go for a mat that can be washed easily for convenience. Hence, it depends a lot on the material.