 Overview—Dental
Unit Water Quality
Drinking water must meet a certain standard with respect to concentrations
of contaminants and chemicals. The maximum concentration of heterotrophic bacteria
set by the EPA, the American Public Health Association (APHA) and the
American Water Works Association (AWWA) is 500 colony-forming
units per milliliter (CFU/ml) of drinking water. The quality of
water delivered by dental units will not meet this standard without regular
maintenance. In fact, research has shown that microbial counts can be
as high as 200,000 CFU/ml within 5 days of installation of new dental
unit waterlines; 1 and, without maintenance, levels as high as 10 6 CFU/ml
of dental unit water have been found. 2,3 The small diameter of dental
waterline tubing, combined with their design and flow rate, enable bacteria
and other microorganisms to form a biofilm that
coats the inside of the tubing. As the water travels through the waterlines
the microorganisms slough off resulting in contamination of the water.
Although there is no evidence that dental unit water is harmful to patients
4 , the CDC has stated that, "Exposing patients or dental health care
personnel to water of uncertain microbiological quality, despite the
lack of documented adverse health effects, is inconsistent with generally
accepted infection control principles."
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The Journal of the American Dental Association
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(June 2004) 