When it comes to water damage there are 3 categories of water depending on the amount of contaminants that may be present. Category 1 or "clean" water, doesn't pose a health threat. Category 2 or "grey water" has some level of contaminants present and may harmful to humans. Category 3 or "black water" is grossly contaminated and may contain bacteria, bloodborne pathogens and chemicals. Due to the areas flood waters flow across during a catastrophic event, they are considered Category 3 due to the contaminants they may pick up along the way. Affected material must be removed. Since drywall often absorbs and "wicks up" water, it must be removed. Cuts are made at 2 feet or 4 feet depending upon the levels of the floodwaters. In this photo, you can see the basement of a home that was damaged during the 2018 floods in Kansas City, Missouri.