ICS Magazine

The Effects of Time - From Category 1 to Category 3

October 15, 2007
Q: Is it correct to assume that a Category 1 water loss that is not attended to for 4 to 7 days or more has changed from a Category 1 to a Category 3




Q: Is it correct to assume that a Category 1 water loss that is not attended to for 4 to 7 days or more has changed from a Category 1 to a Category 3?

A: Recently, our company has received a number of new assignments from insurers and attorneys asking us to review restorers’ invoices, scope of work and overall compliance of restoration/remediation projects with the S500 and S520 Standards.

As a result, we have noticed that there is confusion about the effects of time on Category 1 water damage restoration projects. The S500 describes Category 1 water as water that originates from a sanitary water source and does not pose substantial risk from dermal, ingestion, or inhalation exposure. It is the only Category of water that makes reference to source. S500 later addresses the possible consequences of what can happen if the water intrusion is left unattended for a period of time. However, the S500 does not say to what extent the change will actually occur. The question arises whether it is correct to assume that a Category 1 water loss that is not attended to for 4 to 7 days or more has changed from Category 1 to a Category 3.

The simple answer is, “It depends.”

I recently spoke to a restorer who said, “The S500 says that in seven days a Category 1 water damage changes to a Category 3.” I asked him where in the Standard it says that. He made reference to Figure 1 on page 88 of the 3rd Edition.  He failed to read the text at the bottom of the page, which states:

It is true that some molds can colonize in 72 hours and bacteria can start to multiply in just a few hours. These time frames are based upon ideal growing conditions and not necessarily the conditions that you find in the indoor environment. In some circumstances these microorganisms may take considerably longer to grow due to less favorable conditions. It was not intended for the time frames mentioned here or reflected in this graphic to be absolutes, but a starting point at which you might want to be concerned.

The S500 does not say that Category 1 water turns to Category 3 in any specific period of time. In fact, a Category 1 water intrusion into an uncontaminated indoor environment may never turn into a Category 3. On the other hand, a Category 1 water intrusion into an already grossly contaminated indoor environment may instantly become a Category 3. Whether it does or not is dependant upon whether the water, in conjunction with the environment, has degraded into what is considered “grossly contaminated”.  It may only be “significantly contaminated,” and therefore a Category 2. Examples are given to help clarify what is meant by significantly or grossly contaminated. The definitions are intentionally vague and not absolute. That is not a criticism; the Standard cannot cover every conceivable microbiological condition that might exist in the indoor environment.

Let’s consider what the S500 does say about the deterioration of Category 1 Water over time. 

9.6 Determining the Category of water
It is important to remember that the Category of water initially determined can change during the course of the project (reference Standard Figure 1, To Prevent Amplification of Microorganisms, Prompt Response is Necessary for all Categories of Water Intrusion).

12.1.3 Rapid Response
If sufficient time elapses, Category 1 water can deteriorate to Category 2 or 3 water, requiring that more elaborate procedures . . . be followed.

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.

The definition of “can” in the S500: when the term “can” is used in this document, it signifies an ability or possibility open to a user of the document, and it means that a referenced practice or procedure is possible or capable of application, but is not a component of the accepted “standard of care” to be followed.

While the S500 and S520 definition of “can” refers to a practice or procedure, the common definition of “can” applies when used in other contexts within the document. Category 1 water remaining in a building overtime has the ability, possibility or capability to change to a more contaminated Category. But it is not an absolute as to how contaminated it will become over any period of time. Interestingly, at 12.5.5.3 it explains that:

The degree of contamination represented by a Category 2 water loss can vary from minor (just slightly more contaminated than Category 1 water) to extreme (contaminated just short of Category 3 water).

So, the questions arises: Is it appropriate to have a Category 1 water loss that is left unattended for 4 to 7 days (or more) and then assume that the Category has changed to a Category 3 since there is mold growth? Or has it changed from a Category 1 to a Category 2 and possibly a Condition 3 with the potential of a Condition 2? (Condition 1,2 and 3 are terms defined by the IICRC S520 Standard and Reference Guide for Professional Mold Remediation).

On any Category 1 water intrusion in an uncontaminated building there will simultaneously exist a Condition 1. In other words, in an uncontaminated building that is subjected to a Category 1 water intrusion there concurrently exists a Condition 1. As water is allowed to remain, both "Category" and "Condition" are subject to change.

The answer to the first question (Is it appropriate to have a Category 1 water loss that is left unattended to for 4 to 7 days or more and then assume that the Category has changed to a Category 3 since there is mold growth?)  is “no”. It is not appropriate to assume that a Category 1 water loss that is left unattended for 4 to 7 days or more has changed to a Category 3 since there is mold growth present in the building.

The answer to the second question (Or has it changed from a Category 1 to a Category 2 and possibly a Condition 3 with the potential of a Condition 2?) is “yes” it is possible for a Category 1 to deteriorate to a Category 2 or 3 and possibly develop into a Condition 3 with the potential of Condition 2. However, you should use the appropriate Standard to make decision about the remediation procedures. In my opinion, it would not be appropriate to say that your Category 1 water intrusion that sat for 5 days is a Category 3 because mold might have grown.

Consistently throughout the S500, the reader is directed to the S520 if mold is suspected or discovered. For example, the Foreword states:

This standard also does not address mold remediation; please reference the IICRC S520 Standard and Reference Guide for Professional Mold Remediation for information directly related to mold remediation.

Similar statements can be found in the following S500 Standard sections:

3      Definitions
7.5  Mold
9.6  Determining the Category of Water
9.13.3 Crawlspace Inspection
9.13.4 Basement Inspections
11.2  Indoor Environmental Professional (IEP)
12.5  Drying Contaminated Structures: Category 2 and 3 Water
14.3       Time of Exposure (Contents)


As a final comment about the definition of Category 2 and 3, the reference to contamination has to do with what is in the water and how that water can then impact the structure and contents it comes into contact with. That is not to imply that secondary damage is not possible, it certainly is possible. If you are working on a Category 2 or 3 water intrusion or an otherwise contaminated building, you need to be concerned about the safety of workers and occupants. But, it is important that you clearly delineate between Categories and Conditions as the basis for your decision to remediate.

(Author’s Note: The views presented here are my opinions, and not the official position of the IICRC, the IICRC S500 Standard Committee or the S500 Edit Committee.)