Water damage is classified into categories and classes based on the level of contamination and the extent of damage. Category One water damage comes from a clean water source and poses no significant health risks. Category Two water is significantly contaminated and can cause negative health effects. Category Three water is grossly contaminated and contains harmful agents. On the other hand, the class of water refers to the amount of water and the expected rate of evaporation. Class One damage affects only a small part of a room or area with minimal moisture, while Class Two involves an entire room, including carpet and padding. In Class Three damage, moisture has intruded on the ceilings, walls, floors, insulation, and carpeting. Finally, Class Four involves materials with very low porosity that are wet, such as brick, concrete, and plaster.