What is the problem with hosing tires? Water-specifically “Process Water”. Water that is used in a process, like hosing tires, is classified as process water and must be dealt with as though it is contaminated; because it is, with oil, grease, and various metals. So, if you are going to hose tires, you must plan to collect and dispose of the water legally. Legal disposal means a special processor for treatment and discharge or sanitary sewer.