The cleanliness of the water must be determined for proper remediation. There are three categories of water damage events.
“Clean Water” is from a source that poses no substantial harm to people. Water that overflowed while running your bath water, leaking from a supply line for an ice maker, dishwasher or clothes washer are good examples. This assumes that the surfaces being flooded are reasonably clean. Flooding from clean water is usually treated by extracting standing water. Air movers are set up to create evaporation and dehumidifier's to remove the moisture from the air. A biocide may be applied to prevent mold and bacterial growth. After 48 hours, a Category 1 can become a Category 2.
"Grey Water" poses health risks due to significant levels of contamination of bacteria, mold and/or chemicals. This includes dirty water from washing machines, dishwashers, as well as leaks from water beds, broken aquariums and urine. The water restoration technician should wear some personal protection equipment (PPE). The carpet padding is usually removed and replaced because its sponge-like structure offers the perfect environment for bacterial and mold growth. Due to rampant bacterial breeding and mold growth, Category 2 becomes a Category 3 situation if left untreated for 2 days or more.
"Black Water" contains disease-causing organisms, toxins, and is grossly un-sanitary. Typical black water conditions occur from a sewer back flow, a broken toilet bowl containing feces, and rising flood waters. (Rising flood water is considered Category three because of the possibility of chemicals and organisms found in lawn chemicals, fertilizers, animal feces, decaying ground debris, and over filled sewer and septic systems.)
Tetanus and other serious diseases are likely to be present in rising flood waters. The water restoration technician must wear personal protection equipment. Affected objects such as carpet, padding, and sheetrock must be removed and disposed. A biocide must be applied to kill micro-organisms on site.