Category I (Clean Water)
Clean water floods can result from malfunctioning appliances, toilet holding tanks, and melting snow and rainwater. Clean water residential floods are generally safe for you to clean up yourself, as the water poses no immediate risk to your health. But remember, time is of the essence! Standing water can quickly develop into category II, as there will most likely be dirt and debris in the water which creates perfect conditions for bacterial growth.
Category II (Grey Water)
Sometimes called sullage, grey-water refers to wastewater that is not contaminated with fecal matter. This water contains fewer pathogens than black water, but more than clean water. Grey water can be recycled water or water that is not filtered to the same degree as drinking water (aka potable water). Grey-water floods can be caused by a weather event, an overflowing plumbing fixture or even a broken pipe. At this point, strongly consider hiring a pro and make sure to act quickly as category II water will develop into black water.
Category III (Black Water)
Black-water refers to wastewater contaminated with human waste, food waste, pathogens, toxins, and excessive amounts of dirt or debris. This is essentially sewage-grade water that results from major flooding events caused by hurricane-strength events. Black-water is the most dangerous type and can only be properly resolved by hiring a professional water damage specialist.