Oral Health Group

Pure And Simple: DUWL Solutions

August 31, 2016
by Leann Keefer, RDH, MSM

Providing clean, safe dental water is critical to implementing and maintaining effective infection control protocols. Exposure to poor water quality can pose a health risk for people and conflicts with universally accepted infection prevention protocols. Noted most recently, in 2011 was the fatal case of an 82-year-old otherwise healthy woman who developed Legionnaire’s disease after a dental visit.1 The goal of effective dental unit waterline (DUWL) treatment is to reduce the number of microorganisms present in the water, thereby helping to break the chain of infection.

Dental unit waterline contamination was first reported in 1963.2 Challenges of basic equipment design and tubing contribute to the development of biofilm in DUWL. Research has shown microbial counts can reach <200,000 CFU/mL within five days after installation of new dental unit waterlines.3 Many water samples exhibit colony counts ranging from 1,000 to 10,000 colony forming units per milliliter (CFU/mL), with concentrations greater than 1,000,000 CFU/mL also having been reported.4


The Guidelines for Canadian Drinking Water Quality are established by the Federal-Provincial-Territorial Committee on Drinking Water (CDW) and published by Health Canada. The standard established by the US Environmental Protection Agency (EPA) and other agencies for potable water is 500 CFU/mL of non-coliform bacteria; in Canada, while not a health-based standard, the recommendation for 500 CFU/mL is recognized.

Protocol recommendations for treatment of dental unit waterlines provided by the Alberta Dental Association and College and published in the 2010 document, Infection Prevention and Control Standards and Risk management for Dentistry:

Dental Unit Waterlines

  • All waterlines must be purged at the beginning of each workday by flushing the lines thoroughly with water for a minimum of two minutes.
  • Waterlines must be purged for a minimum of twenty seconds after patient care.
  • Manufacturer’s instructions of the dental units and dental equipment must be followed for daily and weekly maintenance whenever closed water systems or other special water delivery systems are utilized.
  • Suction lines must be aspirated with water or disinfectant solution between patients to reduce likelihood of infectious material backflow.
  • Suction lines must be cleaned once a week with an enzymatic cleaner.

While flushing of dental unit water lines has been recognized as a strategy for reducing planktonic (free-floating) microbial levels in dental water systems, yet the protocol has not been shown to affect the biofilm accumulated on the DUWL tubing.5 Recommendations regarding the efficacy of flushing have changed over the years; in 2003, the CDC Guidelines for Infection Control in Dental Health-Care Setting were amended and no longer supports flushing at the beginning of each day as there was no reliable scientific evidence to show that flushing affects biofilm in the waterlines. However, flushing of all devices connected to the waterlines for 20-30 seconds between patients remains a protocol recommendation.

The following treatment options are available for closed water systems 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

Remaining vigilant to compliance with treatment protocols, including monitoring when required, is critical to achieving and providing safe, clean dental unit water during treatment.


1. Ricci ML, Fontana S, Pinci F, et al. Pneumonia associated wit a dental unit waterline. Lancet 2012;379 (9816):684. April 2012
2. Blake GC. The incidence and control of bacterial infection of dental units and ultrasonic scalers. Br Med J. 1963; 115: 413-416
3. Barbeau J, Tanguay R, Faucher E, et al. Multiparametric analysis of waterline contamination in dental units. Appl Environ Microbiol 1996; 62: 3954–9.
4. Molinari JA, Nelson P. The Need for compliance in Waterline Maintenance. The Dental Advisor 2016; Number 24
5. Porteous NB. Dental Unit waterline Contamination: Causes, Concerns, and Control, Updated 1st Edition; Release date November 2012, Review date October 2015; 9-10

About the Author

Leann Keefer, RDH, MSM
In her role as Director of Education for Crosstex International, Ms. Keefer works to advance Crosstex’s thought leadership among influential dental care professionals. She proactively identifies trends in the fields of oral care and infection prevention, developing and implementing the corporation’s long-term strategies relating to education and professional relations.