Stream of clean – DUWL compliance: Protect your patients and practice

dental waterline treatment
Research has shown microbial counts can reach dangerous levels in dental unit waterlines.

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Best practices of infection prevention and control provide safety in the clinical environment and treatment protocols for patients and dental professionals. Exposure to poor water quality can pose a health risk for people and conflicts with universally accepted infection prevention protocols. 

dental waterline treatment

In September 2016, a pediatric dental clinic in California tested positive for mycobacterium in their on-site water system following an initial confirmed infection in one child and 9 probable pediatric cases. Sixty eight cases have been reported to date, 22 cases have been confirmed and 46 are listed as probable, according to the Orange County Health Care Agency. All of those children were hospitalised at some point. These outbreaks were likely caused by contaminated water used during pulpotomies, which introduced mycobacterium into the chamber of the tooth during irrigation and drilling. Mycobacterium can cause severe infection among immunocompetent children, and because mycobacterium is ubiquitous in the environment, it poses a contamination risk. 


Dental unit waterline contamination was first reported in 1963.¹ Research has shown microbial counts can reach >200,000 CFU/mL within 5 days after installation of new dental unit water-lines² and contamination levels of up to 1 million CFU/mL of dental unit water have been documented. ³,4 In 2011, the fatal case of an 82-year-old otherwise healthy woman who developed Legionnaire’s disease after a dental visit6 was reported. 

The goal of effective dental waterline treatment is to reduce the number of opportunistic microorganisms present in the water, thereby helping to break the chain of infection. Based on standards for potable drinking water by the Environmental Protection Agency, the American Public Health Association, the American Water Works Association, and the Centers for Disease Control and Prevention guidelines (2003) state the number of bacteria in water used as a coolant/irrigant for nonsurgical dental procedures should be less than 500 CFU/mL.5

dental waterline treatment

Water flowing through long and narrow dental unit waterlines (DUWL’s) can harbor dangerous bacteria. When untreated, or improperly maintained, these contaminated DUWL’s can potentially harm your patients, your staff and your practice’s reputation. 

Chemical agents commercially available are designed to inactivate or remove biofilms or deter attachment of biofilm in new or cleaned systems. 

The following options are available to address the biofilm with its resident microorganisms and optimize dental unit water quality:

  • Self-contained water systems
  • Point-of-use filters
  • Chemical treatment protocols
  • Municipal water treatment systems
  • Slow-release cartridge devices

Effective dental unit waterline maintenance is a key component of an infection control program. Understanding the risk involved with biofilms and contaminated aerosols compels us to remain compliant with treatment protocols. Criteria for choosing a dental unit waterline treatment system includes ability to control microorganisms and biofilm at required standards, product and labor costs, safety to equipment and the environment, and most importantly, compliance to provide safe, clean dental unit water during treatment.

Leann Keefer, RDH, MSM / General Manager and Director of Education, Crosstex International

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1 Blake GC. The incidence and control of bacterial infection of dental units and ultrasonic scalers. Br Med J. 1963; 115: 413-16

2 Barbeau J, Tanguay R, Faucher E, et al. Multiparametric analysis of waterline contamination in dental units. Appl Environ Microbiol 1996; 62: 3954–9.

3 Mayo JA, Oertling KM, Andrieu SC. Bacterial biofilm: a source of contamination in dental air-water syringes. Clin Prev Dent 1990; 12:13–20.

4 Santiago JI. Microbial contamination of dental unit waterlines: short and long term effects of flushing. Gen Dent 1994;42:528–35

5 Centers for Disease Control and Prevention. (2003). Guidelines for Infection Control in Dental Health-Care Settings. Retrieved

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