There are three basic “types” of water damage, based on the level of contamination. 1-Category 1 (Clean Water): from a damaged pipe or hose. 2-Category 2 (Grey water): this is from an overflowing washing machine or dishwasher or sump-pump failure. 3-Category 3 (Black Water): sewage and all flooding where the water comes into the home from the outside. This water is grossly contaminated. No porous materials damaged by such water can be saved. Such a loss may involve some demolition of drywall that has been contaminated.