A milk hauler is a person. Milk haulers pick up milk in a milk truck every two days and transport it to a dairy processing plant. The trailer tanks on the trucks are stainless steel and insulated to keep the milk cold. Each milk hauler is a licensed milk grader, which means they have learned about and follow the rules and regulations that make sure milk is handled safely. They must follow strict schedules to make sure that milk is delivered promptly to the plant. A milk hauler often picks up milk from several farms and takes a full load to the dairy processing plant.