ICS Magazine

Wind-Driven Rain and Category 3

March 11, 2008


Q: I’ve noticed that the current version of the S500 now includes wind-driven rain as part of Category 3. Does that mean that wind-driven rain is always considered contaminated?

A: Your observation that the current edition of the “IICRC S500 Standard and Reference Guide for Professional Water Damage Restoration” (3rd Edition) includes a reference to wind-driven rain, as a part of Category 3, is correct. The 2nd edition of S500 reads as follows:

3 Definitions
category 3 water: grossly unsanitary water arising from sewage or other contaminated water sources and having the likelihood of causing discomfort or sickness if consumed by or exposed to humans. This category includes all forms of seawater, ground surface water and rising water from rivers or streams. Also referred to as “black water.”

5.3 Category 3 – Black Water
Category 3 water is referred to as “Black Water.” Black water contains pathogenic agents and is grossly unsanitary. Black water includes sewage and other contaminated water sources entering or affecting the indoor environment. Gray water that is not removed promptly from the structure and its contents may be reclassified as black water. Toilet backflows that originate from beyond the toilet trap is considered black water contamination, regardless of visible content or color.

Category 3 water includes all forms of flooding from seawater, ground surface water and rising water from rivers or streams. Such water sources carry silt and organic matter into structures and create black water conditions.

The water is considered to be category 3 water in situations where structural materials and/or contents have been contaminated with such contaminants as pesticides, heavy metals, or toxic organic substances.


The S500 3rd Edition was changed to:

Category 3 - Category 3 water is grossly contaminated and can contain pathogenic, toxigenic or other harmful agents. Examples of Category 3 water can include, but are not limited to: sewage; toilet backflows that originate from beyond the toilet trap regardless of visible content or color; all forms of flooding from seawater; ground surface water and rising water from rivers or streams, and other contaminated water entering or affecting the indoor environment, such as wind-driven rain from hurricanes, tropical storms, or other weather-related events. Such water sources may carry silt, organic matter, pesticides, heavy metals, regulated materials, or toxic organic substances. The phrase in question is “and other contaminated water entering or affecting the indoor environment, such as wind-driven rain from hurricanes, tropical storms, or other weather-related events.” This phrase can be read in different ways.

First, the reader may assume the phrase means all “wind-driven rain from hurricanes, tropical storms, or other weather related events” is contaminated; another interpretation might be that the phrase lists possible other sources of contaminated water.

When reading any document, it is important for the reader to consider the context in which statements are made. In this case, the second sentence of the Category 3 definition in the 3rd Edition says that, “Examples can include.” According to the American Heritage dictionary, the word “can” is defined as there being a “possibility” under the specified circumstances. Therefore, it is not an absolute.

The S500 elaborates on what is included in determining the Category of the water in the following section:

12.1.8 Determining the Category of water
The Categories of water, as defined by this document, refer to the range of contamination in water, considering both its originating source and its quality after it contacts materials present on the job site. Time and temperature can also affect the quality of water, thereby changing its Category. Restorers should consider potential contamination . . .

Notice, the phrase in question states, “contaminated water” is “entering or affecting the indoor environment.” There are two key factors to consider. First, is that the water is “contaminated.” If it is contaminated then yes, it is a Category 3. However, what if the wind-driven rain that enters is not contaminated? Then, in my personal opinion, it is not a Category 3. Secondly, what if the water that enters is not initially a Category 3 and is allowed to remain for a period of time without any mitigation or restoration? In my opinion, it can become a Category 3 if the levels of bacteria are allowed amplify to a point where there is gross contamination. As I stated in response to a similar question published in this magazine in October 2007, “It is possible for a Category 1 [or 2] to deteriorate to a Category 2 or 3 and possibly develop into a Condition 3 [mold growth].”

The problem is that restorers need to make a preliminary determination at the commencement of work as to whether to employ procedures necessary for Category 3 or Condition 3 (mold) remediation. The Standard provides examples for restorers to use as initial guidance in making that “preliminary determination”. Therefore, it would be reasonable for a restorer to assume wind-driven rain could be a Category 3 and proceed accordingly. However, if there is a question as to whether it is actually a Category 3, then the standard provides for a mechanism to answer that question. The only way to make such a determination is to perform an assessment (e.g., sampling and laboratory analysis).

9.8 Developing a Preliminary Determination
In most cases pre-remediation assessment by an IEP on a water damage restoration project is not necessary. However, if the preliminary determination shows that one or more of the following elevated risk situations are present and the damage is Category 3, then restorers should consider using an IEP to make a pre-remediation assessment. Considerations may include:
  • occupants are high risk individuals; or
  • a public health issue exists; or
  • there is a risk of adverse effects on worker or occupant health; or
  • occupants express a need to determine the identity of a suspected contaminant; or
  • contaminants are believed to have been aerosolized; or
  • there is need to determine, rather than assuming, that the water actually contains microbial contamination.

(Notice the last bullet point partially addresses this issue.)

In conclusion, the S500 does provide examples in order to assist restorers in making a preliminary determination. The examples are not definitive or absolute. An assumption can be made based upon the examples provided. However, the only definitive way to make such a determination is to have an assessment of the water performed by an IEP.

The views presented in this article are my personal opinions, and not an official position of the IICRC, the IICRC S500 Standard Committee or the S500 Edit Committee.