No, They are not designed to be used as filters. There are many ways that paper towels can be harmful to your health. You should never use them to filter your coffee or anything else that you drink. You may not know that paper towels were actually designed to be used as toilet tissue. Toilet paper has very tiny holes in it, which allows it to drain quickly and easily. When you use a paper towel as a filter for your coffee or tea, you are introducing bacteria into the beverage.