Clean water is water that does not pose an immediate health threat. This applies to waters that do not contain contaminants, including water from includes broken water lines, malfunctioning appliances, toilets holding tanks, snow melt and rain. However, over time, say within 48 hours, and especially after contact with building surfaces, clean water can progress to category two, gray water.

Grey water may cause a health risk since the waters may contain chemical or biological contamination. These waters include discharges from dishwashers, washing machines, sinks, showers, aquariums and waterbeds. Again time is of importance, after 48 hours in contact with building surfaces, most gray water should be reclassified as category three, black water.

Black water is a positive health risk. This water is presumed to contain multiple and potentially harmful contaminants. It includes floodwaters containing soil and any sewage waters. All raw sewage is contaminated with microbes, including bacteria, protozoans, molds, fungi and viruses. Many of these are pathogenic to humans. Microbes from this source certainly cause many diseases, including Cholera, Typhoid, Hepatitis, and numerous other gastroenteritis type illnesses. Common symptoms include diarrhea, vomiting, nausea, fever and severe abdominal cramps. Contamination from fecal matter also includes the so-called “cruise-ship virus”, correctly called Norovirus, and parasitic illnesses due to infections from Giardia or Cryptosporidium. Any contact with contaminated water or surfaces can lead to contamination of the skin and subsequent transfer to the mouth. During and after the drying out process, unless proper precautions are taken, infections may occur through the inhalation of microbes contaminating aerosols and airborne dusts. Even the dusts themselves may trigger allergies in sensitized individuals.