There are three basic types of water: service grade water, working grade water, and drinking water. Service grade water is untreated, and should not be used for tasks within the home. Service grade water is typically used for watering lawns & plants, washing your patio or driveway, or other outdoor activities. Working grade water undergoes water treatments, and is safe to use inside your home. The typical household has working grade water. This water is used for washing clothes, dishes, and general household cleaning. The most pure water is drinking water. Drinking water can be consumed without the risk of immediate or long-term harm. Since 75% of the human body is made up of water, it is essential for you to use drinking water when you cook and drink.