Categories and Classes-Of Water Damage

Understanding The Categories and Classes-Of Water Damage

There are currently standards in place from the Institute of International Cleaning and Restoration Certification (IICRC) and the American National Standards Institute (ANSI) that must be adhered to at all times. These are the standards all companies within the industry must maintain in order to receive certification.


Of these standards, the current one that deals with water damage restoration is known as the S500. This stands for the Standard and Reference Guide for Professional Water Damage Restoration. In this category, it goes on to describe the three different degrees of contamination that may occur. These help providers to determine the restorability of any item that has been impacted by water damage, in addition to the need for certain personal protective equipment (PPE).

Category One

For category one, the water has originated from what is perceived to be a clean or sanitary source of water. It is not believed that this water source has any risk of ingestion, dermal, or inhalation exposure. This is typically water that comes from supply line pipes, snow, rain, ice, and other sources that have no potential for contamination.

Category Two

In the second category, water may have a significant amount of contamination in it. This offers the potential for a person to experience sickness or discomfort should they consume it. In this case, the water is believed to have an unsafe number of microorganisms in it, along with the nutrients they need. This is either chemical or biological. This water may contain no fecal matter and only minor amounts of urine from a toilet trap. Waterbeds, toilet bowls, washing machines, and dishwashers are examples of where this water could potentially come from.

Category Three

If water falls in category three, it has been contaminated to excessive levels. This contains pathogenic, harmful agents, and toxigenic material. This is sewage that comes up through the toilet, regardless of color, flooding from rivers, seas, or streams, and water caused by tropical storms. This may also include items that have contaminants it carries in with it that are considered toxic or harmful.

It’s important to understand that the initial categorization of this water, does not mean that is where it will remain. Category 3 water doesn’t improve in danger, but categories 1 and 2 can quickly deteriorate. This occurs when there are microbial organisms that enter it, the length of time the water has set, and other real world factors the water encounters. It is important to pay attention to any changes and address these changes with appropriate gear and handling.


As part of S500, there is an additional classification of the water intrusion. This deals with the amount of water that is left behind after extraction. This water still needs to be evaporated, in order to finalize the process. With this classification you have an initial amount of dehumidification that will be required to address it.

Class One

When a space is listed as a Class 1 water intrusion, it means that a minimal amount of water has entered the area. The materials and the area are considered low porosity. This means that after the bulk of the water is taken from the area, there is a need for only minimal evaporation, then the space is considered to be dry.

Class Two

For a Class 2 water intrusion, there is a measurable amount of water that has entered the area. When the excess water is removed, there is still a medium or high porosity material that must be addressed. This includes things like carpet. This requires additional time for the area to dry out. However, the area impacted is only located where the water actually went across the floor and absorbed into direct contact areas.

Class Three

In a Class 3 water intrusion, there is what is considered to be the largest amount of water absorption taking place. This has the highest rate for evaporation needed after the bulk of the water has been removed from the space. This affects structural surfaces and may also include ceiling boards, walls, and carpeting in the home.

Class Four

When you have a Class 4 water intrusion, the water and moisture is trapped or even bound within the local building materials. There is also a low potential for there to be evaporation. This includes hardwood, concrete, plaster and similar surfaces. In these cases, you need to plan on longer times for drying and the use of alternative methods to help remove the moisture from the space.

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