Water Damage Categories and Classes Explained 

Water Damage Categories Clean Grey Black Icon

When reading and learning about water damage mitigation, you will notice that leaking water and floods are discussed in terms of Category and Class. 

Learning how to recognize different types of water will help you stay safe when water accidents and flooding occurs. 


Category Classifies the Cleanliness of the Water

The Category classification describes the level of cleanliness of the water. There are three different categories - Clean, Grey and Black.   


Category 1 "Clean Water"

Water leaking from a clean (sanitary) source, like a faucet or toilet tank is referred to as Category 1 or Clean Water.

This category of water is considered safe to drink, touch and breathe in. You do it every day.


Examples of Clean Water include:

  • Overflowing bathtub or sink
  • Leaking water hose (for ice maker, dishwasher, washing machine)
  • Melting ice or snow
  • Falling rainwater
  • Leaking toilet tanks
  • Toilet bowls that do not contain contaminants or additive 


    You can dry Clean Water leaks yourself with XPOWER drying tools and 3-Step Water Mitigation Process.

    If you don't start drying immediately, water damage of Category 1 can turn into Category 2 within just 48 hours. 

    The time and cost for reconstruction and restoration will only increase the longer you wait to mitigate.


    Note! Clean water may become contaminated after it has left its original source and been in contact with other surfaces or materials.


    Category 2 "Grey Water"

    This dirty water category contains bacteria or mould or even chemicals. Avoid touching or ingesting this type of water (it would probably make you barf!).


    Examples of Grey Water include:

    • Water from dishwashers and washing machines
    • Leaking water beds
    • Leaking sink drains
    • Broken aquariums
    • Toilet water containing urine
    • Clean Water that isn't promptly removed


    If you need to be in contact with Grey Water, you should wear a protective mask, gloves and clothing. 

    The damages of Grey Water calls for more extensive mitigation and restoration. For example, your carpet will likely have to be removed and replaced to prevent mould from thriving under your floor.  

    Immediately call for professional help. If the leak isn't mitigated within 48 hours, Category 2 water can turn into Category 3 water.


    Category 3 "Black Water"

    Category 3 water is grossly contaminated and ridden by disease-causing organisms and bacteria. It can cause severe illness or even death if ingested.


    Examples of Black Water include:

    • Sewer backflow
    • Toilet water containing feces
    • Seawater
    • Grey Water that is not promptly removed
    • Rising floodwaters


    Rising floodwater is considered Black Water, because it may contain chemicals and organisms from lawn chemicals, fertilizers, animal feces, overfilled sewer systems etc.

    Black Water damage requires very extensive and careful restoration.

    Carpets, paddings and drywalls in the flooded area must be removed and disposed of. A biocide must also be applied to kill all micro-organisms. 


    Class Describes the Level of Difficulty in Removing the Water

    Classes of water loss are arranged by the difficulty and time needed to dry out an area.

    There are four different Classes of water, spanning from Class 1 (lowest level of difficulty) to class 4 (specialty drying situations). 

    The determination is based on A) the amount of water present and B) the type of material that is absorbing the water. 

    Determining the class will subsequently determine the amount and type of drying equipment that is needed to dry out the structure.


    Class 1 - Lowest Level

    For water loss to be classified as Class 1, only a portion of the room will be affected by water. There is very little carpet or other absorbent materials in the room. There is barely any wicking up the wall. 


    Class 2 - Intermediate Level

    For Class 2 water damage, water will have spread throughout the entire room. The carpet and pad are wet and water has wicked up the walls (but less than 24 inches). 

    Water and moisture have also been absorbed into structural materials and furniture.  


    Class 3 - Highest Level

    Class 3 cases typically involve water from overhead, such as a broken sprinkler system or an upstairs plumbing failure.

    Walls, ceilings, insulation, floors, carpets and cushions are soaked. 

    Next to Specialty Drying Situations, this is the most extensive water loss to tackle.


    Class 4 - Specialty Drying Situations

    Class 4 is typical for water damaged hardwood floors, concrete, crawlspaces, behind cabinets or inside of walls. 

    In these cases, moisture is persisting in material or is inaccessible by conventional drying methods. 

    For this class of water loss, longer drying times and specialty water damage restoration equipment such as Wall Cavity Dryers, Confined Space Fans and Mini Air Movers are required.  


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