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The Three Categories of Water Damage

Our industry has an S500 book, produced by the IICRC. This is an ASNI developed standard of care for our industry. Insurance adjusters as well as contractors all consider this the definitive authority when it comes to our water mitigation, cleaning, and restoration work in our industry. It's what we base everything on when we come in and perform an inspection and the preceding water mitigation services.

A couple questions to ask any restoration company: If it’s not in the s500, why are you doing it? If it is in the standard of care, why aren’t you doing it? Too many times we see other companies not doing things according to these standards. There are many different reasons why we do what's outlined in the book, but, the most important reasons usually boil down to health and safety. It is amazing the potential effects that a simple water leak can have on the health and safety of a building and its occupants.

Moisture Content, Class, and Category. All of these things are classified and defined in our industry standard of care. So, when we talk about water, water loss, and water damage, these are the key points we always use.

Categories of Water Damage

There are four classes of water, and three categories of water. Now, a lot of people have heard of some of these categories of water, but they might not really know what they are, or may know them, but they could be labeled differently. Here's the breakdown of each one and what it means regarding cleanup and restoration.

Category One

There’s category one, which is potable, drinkable, no contaminants, clean water. So a category one water loss would be something like a supply line that goes to your faucet, a sink overflow, or falling rainwater. Ask yourself, ‘could I drink it and not get sick?’. The definition from the S500 states, “Category 1 water originates from a sanitary water source and does not pose substantial risk from dermal, ingestion, or inhalation exposure.”

Category Two

Category two water means significant contaminants. Some people also sometimes refer to category two water as “gray water.” This could be a dishwasher or washing machine drain line, so it’s clean water, but then mixed with some bits of food or soap or something like that. Some examples of category two could even be the overflow of water in the bowl of a toilet, assuming it’s not a backup of the sewer system or there is feces in the bowl. Even trace amounts of urine are acceptable in category two, so it’s gross, but that’s where it lands. Category 2 water is defined as containing, “significant contamination and has the potential to cause discomfort or sickness if contacted or consumed by humans.”

Category Three

Category three, also referred to as “black water”. Some people say category three is sewage, however, that is inaccurate. Sewage is category three, category three is not always sewage. Category 3 water is “grossly contaminated and can contain pathogenic, toxigenic or other harmful agents and can cause significant adverse reactions to humans if contacted or consumed.” Some examples of category three water, right from the IICRC S500 book would be wasteline backflows, seawater, rising waters from rivers or streams (like the local Chattahoochee River here in Gwinnett County), and wind-driven rain. Now, you may be thinking, ‘rain? Didn’t I just read in this article above that falling rainwater was category 1? I thought rain was pure and clean, how can it be category 1 and category 3?’ However, take note of the difference between the two. Falling rain, and wind-driven rain. Wind-driven rain from large storms and hurricanes can often pick up tons of contaminants on its way down through our atmosphere, and then, when wind driven into your home, it comes through your shingles, tar paper, plywood, insulation, and other building materials. That once clean, pure rain is driving through whatever’s in the atmosphere, on the roof, and in the building materials. That’s why wind-driven rain can be category 3 water.

Now, just because something can be category 3 doesn’t mean it always is category 3. If you have a water spot on your ceiling the best way to determine it, is by considering the type of storm related to the leak, looking at the color of the water or stain, the items it traveled through, and if possible perform ATP testing or a similar test to determine the amount of possible contamination. Most people do not take the time to consider all of these factors and this may lead to the stain showing through or mold growth coming from the contaminated water.

Groundwater can also be category 3 water. Any kind of groundwater that seeps into your home needs to be properly assessed. If standard category 1 rainfall runs on the ground and enters the home, then how is groundwater potentially category 3? Groundwater can have pesticides, animal droppings, manure, and more. The main thing is, just consider the whole situation and possibly even perform some testing prior to making a decision as to the category of water.


Finally, sewage. Sewage is definitely category 3. Gross amounts of contaminants. The IICRC also specifies when it comes to the definition of category 3 water, “can carry trace levels of regulated or hazardous materials”, the example includes pesticides, toxic organic substances, etc. Since category 3 water is defined as being grossly contaminated, then it doesn’t matter if it is contaminated by sewage, regulated hazardous materials, mold, or any other type of bacteria or organic substance, it all falls into the same category of water… The only difference is, depending on what made it cat 3 water, there may be additional protocols and procedures to handle the situation as a whole and not just rely on the standard cat 3 water protocols. Other regulated hazardous materials could be lead, asbestos, mercury, arsenic, all pesticides, fuels, solvents, and more. So, category three has a very broad definition and we have to be careful with what we’re looking at and how it is handled.

Always Changing

A category one, clean water, can change to a two or a three easily. One way is simply over time. Time and temperature can change the category of water from one all the way to three depending on what microorganisms were present and became wet. If you let water sit stagnant in your building it’s gonna change over a few days, you may start to notice a sour or musty smell. You can go from one to three quickly because mold starts growing and colonizing wherever it has food, water and moisture.

A Dirty Story

I’ll give you an example of category 1 water changing into category 3. We had a home where the person was a hoarder. They had animals running loose. The source of the water was a clean water supply line leak at the sink. However, the water ran through all sorts of dirt, filth, and feces that was there because the animals were just running around. And guess what, instant cat three. It can change just that quickly.

What Category Is It?

When discussing category of loss with insurance claims representatives we often hear, “If it came from a supply line, that’s got to be a category one loss”. Well, if you’re only looking at the supply or the source of origin you may be right, but not when you’re looking at everything else. So let’s look at the big picture and make sure we get the assessment right, it means your health and safety as well as the health and safety of the ones doing the work. 


If a water loss is a cat 3 instead of a cat 1 there are major differences in how the work is handled. Differences from what or how much containment is setup, personal protective equipment is worn, what type of cleaning or demolition is done, what equipment is used and even the use of different disinfectants or cleaning agents. This means the cost typically increases with a category 3 water loss. For an insurance company only focused on the additional costs, they may push to label a loss incorrectly as a cat 1 or 2 instead of a cat 3. I get it, I try to be frugal and save money every chance I get too, but it’s not the only thing to consider. For a restoration company like R4 Restoration, it means a lot of added work, disinfecting, added liability, health and safety concerns, and more. As well as being an IICRC Certified Firm, we’ve agreed to their code of ethics and to follow the standard of care. By not performing water mitigation work properly we could lose our designation.

Last, but certainly not least, as a homeowner, proper identification and treatment of the category of water is a major concern for the health of the home and your family. The difference between handling category one and category three comes down to the method of cleaning.

Cleaning with Force

One of the major differences with handling category three is typically demolition. Demolition is labeled as a method of cleaning by the IICRC. It’s physical removal of contaminated or dirty structure. It could be drywall, insulation, or something like that.

Bigger, Not Better

Now that we explained category 3 water losses typically cost more, the typical reaction would be that we want to find a way to label all jobs as cat 3 right? Wrong… Although we will handle all categories of loss, the projects we want to do as a restoration company are category 1 and 2. Why if it’s usually a bigger dollar amount on a category 3 loss would we not want it to always be category three? It comes down to a few things. One, we don’t want to do demolition. Demo costs a lot of money, not just for the homeowner and insurance company but also for us. Demo is the most labor-intensive portion of a project and takes our time away from other jobs and customers. Two, we have dump fees, haul off, and all this other stuff that adds to the project.  As a restoration company we make a better margin on category one and two jobs since our costs are lower on those. So, we never push a project into category three just to try to bump up the dollar amount. If we say something’s category three, then we have to do a lot more work for less margin and we don’t want to do that. It also typically extends the timeframe of the entire job and may displace you from your home, it really doesn’t help anyone. The quicker we complete the entire project, the less disruptive it is for you, the happy you are and the better review you’ll give us!

Call the Experts at R4!

Don’t get overwhelmed, there are professionals that can assist with all aspects of the restoration process. An expert will be able to help you with everything from the initial inspection, to identifying the source of loss, documenting, and cleanup work. Everything is done according to IICRC industry standards, while on call 24/7/365.




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Suwanee, GA 30024
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