The Sources, Categories, and Classes of Water Damage


Water may enter a building or home by a number of routes. It may be from either external or internal sources. The water may be relatively clean or contain some degree of contamination.

Damage from wind storms or other causes may allow rain water to enter through the roof. Ice dams on sloped roofs can force water to travel under roofing material and into the building.

Poor construction methods, faulty plumbing, or water pipes that freeze and burst can result in water where it was never intended to be. The water may come from lines carrying potable (safe for drinking) water or the source could be a backed-up sewage line. Faulty appliances or damaged water beds may also be the cause of a water loss. Flooding due to rising rivers or storm surge is another source.

The cause may be due to accident, negligence, or even intentional vandalism. A water loss is often associated with a fire loss due to the water used to control the fire.

High water tables and capillary action may result in ground water rising into a building through the foundation. Hydrostatic pressure (the force of water in the ground outside a building) can push water into a concrete foundation. From there, water can find its way to other parts of the structure.

Damage may even occur without coming in contact with liquid water. Hygroscopic (moisture absorbing) materials will attract moisture from the air during prolonged periods of high humidity.

In water damage terms, categories are described as the range of contamination in the water, considering both the source and changes in quality due to coming in contact with contamination on the job site. The effects of time and temperature are also considered.

Category 1 - sometimes called "clear water", originates from a sanitary source and does not pose any substantial risk to human health either through ingestion (drinking the water), contact with the skin (dermal exposure) or inhalation.

Examples can include, but are not limited to:

- broken water lines

- tub or sink overflows with no contaminants

- appliance malfunctions involving water supply lines

- melting ice or snow

- falling rainwater

- broken toilet tanks

- toilet bowls that do not contain contaminants or additves

Over time, this category may deteriorate into Category 2 or even Category 3 water. How soon this happens depends on environmental conditions.

Category 2 - may also be called "gray water". It contains significant contamination and has the potential to cause discomfort or sickness if contacted or consumed by humans. The contamination may be chemical, biological, or physical in nature, as well as including organic matter, substantial numbers of microorganisms and/or nutrients that would encourage the growth of microorganisms.

Examples can include, but are not limited to:

- discharge from dishwashers or washing machines

- overflows from washing machines

- overflows from toilet bowls on the room side of the trap with some urine but no feces

- seepage from hydrostatic pressure

- broken aquariums

- punctured water beds

Category 3 - sometimes known as "black water". This category is grossly contaminated and can contain pathogenic, toxigenic, or other harmful agents. It poses a significant health risk.

Examples can include, but are not limited to:

- sewage

- toilet backflows that originate from beyond the toilet trap regardless of visible color or content.

- all forms of flooding from seawater.

- ground surface water and rising water from rivers or streams

- other contaminated water entering or affecting the indoor environment such as wind-driven rain from hurricanes, tropical storms, weather-related events

- above sources carrying silt, organic matter, pesticides, heavy metals, regulated materials, or toxic organic substances


When describing a water loss, the term "class" is used to indicate the size of the affected area, the amount of water present and the expected rate of evaporation for the particular materials involved. Each type of material will absorb varying amounts of water and then release the water at different rates.

- Class 1 (least amount of water, absorption, and evaporation) Water losses that affect a relatively small area with minimum moisture absorption by materials, and has a lower potential rate of evaporation. Little or no wet carpet is present. It may affect only part of a room or area.

- Class 2 (large amount of water, absorption, and evaporation) Water losses that affect a significant area with moisture absorption by highly porous materials, such as wet carpet and cushion with water that may have wicked up into the walls, generally less than 24 inches. Moisture will also be present in other less porous structural materials including concrete, plywood, particle board and framing lumber.

- Class 3 (greatest amount of water, absorption and evaporation) This involves the greatest amount of water and the fastest rate of evaporation. Water may have come from overhead, so this includes the ceilings and walls becoming wet.

- Class 4 (specialty drying situations) This includes water trapped, hidden, or bound inside dense materials such as hardwood floors, cabinets, plaster, brick, masonry walls and/or concrete. Even though a relatively small amount of water may be involved, restoration of a Class 4 loss normally takes longer than a Class 1 job.

Thank you very much for taking the time to read all of this valuable and important information that is related to water damage situations.

If you notice any sign of water damage in your home, place of work, or anywhere else, please call us right away at 1 (800) 848-8385, and we will come to inspect as soon as we possibly can.