October 3, 2012

Water & Moisture

»Testing for Mould
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You may be wondering –  Is it possible that water or moisture is impacting my property?

As we all know, there are three (3) forms of water: solid (ice), liquid, gas (vapor).  Due to the various forms of water, moisture accumulation can occur in your property due to indoor plumbing leaks, water intrusion (from outside source), elevated relative humidity, inadequate air circulation, frost/ice from frozen pipes, etc.

As water loss experts, American Metropolitan Environmental, Inc. (AMEI) can determine the categorization of the water loss (IICRC S500), identify the extent of water damage, and submit a comprehensive report that includes the scope of work to assist you, and your insurance (when necessary), in restoring your property to a Pre-Loss Condition.  Essential tools in identifying sources and extent of moisture accumulation are the Protimeter MMS© (moisture meter) and Infrared Camera (FLIR).


In many situations, it’s not the initial moisture accumulation or water loss episode that causes problems to the interior, but rather the length of time that the moisture is present.  The longer that building materials remain wet, the more deterioration can occur, thus eventually promoting microbial growth (mould/bacteria) in as little as 24 to 48 hours.

In some situations, the source of the water loss can be of great concern!

Categorizing the level of water contamination is required to appropriately perform a loss assessment and evaluation.  The category of water contamination must be considered so that procedures can be established for processing water-damaged structures and materials safely. 

Water damage is divided into three (3) general categories: Category 1 – Clean Water, Category 2 – Gray Water, and Category 3 – Black Water.  Note: the category of water contamination is not determined by the color of the water, rather the category is determined by the source, contents, history and characteristics of the water.  The following definitions for water damage are extracted from the ANSI/IICRC S500-2015 Standard for Professional Water Damage Restoration document ( http://iicrc.org/standards/iicrc-s500/)

  • Category 1 – Clean WaterCategory 1 water is referred to as “Clean Water”.  Clean water originates from the source that does not pose substantial harm to humans.  Examples of clean water sources may include, but are not necessarily limited to, broken water supply lines, tub or sink overflows with no contaminants, appliance malfunctions involving water supply lines, melting ice and snow, falling rainwater, broken toilet tanks and toilet bowls that do not contain contaminants or additives. Clean water that has contact with structural surfaces and content materials may deteriorate in cleanliness as it dissolves or mixes with soils and other contaminants, and time elapses.  Category 1 Clean Water can quickly migrate to Category 2 Gray Water.

  • Category 2 – Gray WaterCategory 2 water is referred to as “Gray Water”.  Gray water contains a significant level of contamination and has the potential to cause discomfort or sickness if consumed by or exposed to humans.  Gray water carries microorganisms and nutrients for microorganisms.  Examples of gray water sources may include, but are not necessarily limited to, discharge from dishwashers and washing machines, overflows from washings machines, overflow from toilet bowls with urine (feces), sump failures, seepage due to hydrostatic pressure, broken aquariums and punctured water beds.  Gray water may contain chemicals, biocontaminants (fungal, bacterial, viral, algae) and other forms of contamination including physical hazards.Time and temperature aggravate Category 2 Gray Water contamination levels significantly.  Gray water in flooded structures that remains untreated for longer than 48 hours may change to Category 3 – Black Water.

  • Category 3 – Black Water Category 3 water is referred to as “Black Water”.  Black water contains pathogenic agents and is grossly unsanitary.  Black water may include sewage and other contaminated water sources entering or affecting the indoor environment.  Category 2 Gray Water that is not removed promptly and properly from a structure may be reclassified as Category 3 Black Water within a short period of time.  Toilet backflows that originates from beyond the toilet trap is considered black water contamination, regardless of visible content or color. Category 3 Black 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 creates black water conditions.


Vapor, or relative humidity (Rh), can be naturally occurring such as outdoors during a rain, in the warm summer months, or it can originate from man-made sources such as showers, vaporizers, utilization of air-conditioning, improperly functioning humidifiers, etc.

When it comes to relative humidity, there is no “ideal” humidity level and temperature suitable for all building occupants. Many factors, such as personal activity and clothing may affect personal comfort. There is considerable debate among researchers, IAQ professionals, and health professionals concerning recommended levels of relative humidity.  In general, the range of indoor humidity levels recommended from ASHRAE Standard 55-2017 is 30% to 50%.  Relative humidity levels below 30% may produce discomfort from dryness whereas indoor relative humidity levels above 62% have been documented to produce environments ideal for the proliferation of fungi (mould) on surfaces.

ASHRAE documents Ventilation for Acceptable Indoor Air Quality (ANSI/ASHRAE Standard 62.1-2016) and Thermal Environmental Conditions for Human Occupancy (ASHRAE 55-2017)


In some situations ice forming on exterior surfaces such as windows, siding, roofing, guttering, etc. can cause moisture infiltration into a structure, create condensation on windows, and even reveal unknown roof leaks.  In addition, in lower temperatures, outdoor faucets and hoses can freeze causing domestic supply plumbing lines to rupture and flood crawlspaces, wall cavities, basements, etc.

For further information on Phases of Water, see the following information from NASA:


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