Types of Water Categories
There are three basic categories of water damage, based on the level of contamination.
Category 1 Water - Refers to a source of water that does not pose substantial threat to humans and classified as "clean water". Examples are broken water supply lines, tub or sink overflows or appliance malfunctions that involves water supply lines.
Category 2 Water - Refers to a source of water that contains a significant degree of chemical, biological or physical contaminants and causes discomfort or sickness when consumed or even exposed to. Known as "grey water". This type carries microorganisms and nutrients of micro-organisms. Examples are toilet bowls with urine (no feces), sump pump failures, seepage due to hydrostatic failure and water discharge from dishwashers or washing machines.
Category 3 Water - Known as "black water" and is grossly unsanitary. This water contains unsanitary agents, harmful bacteria and fungi, causing severe discomfort or sickness. Type 3 category are contaminated water sources that affect the indoor environment. This category includes water sources from sewage, seawater, rising water from rivers or streams, ground surface water or standing water.
Category 2 Water or Grey Water that is not promptly removed from the structure and or have remained stagnant may be re classified as Category 3 Water. Toilet back flows that originates from beyond the toilet trap is considered black water contamination regardless of visible content or color.
our source: wikipedia