As you may have deduced from our prior blogs, Category 3 Water is considered the most hazardous. - It is also referred to as "black water" and is the most unsanitary. This water poses significant health risks and can come from a variety of sources. Sources such as a sewer backup, or other forms of contaminated water intrusion. It may contains unsanitary agents, harmful bacteria and fungi, causing severe discomfort or sickness. It is recommended that a water loss which involves Category 3 water be handled only by a trained, professional company.