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Best Practices For Maintaining Safe Dental Unit Waterlines

Updated: Apr 5


How to keep your dental unit waterlines clean and safe.
We’ve been loud about dental unit waterlines and patient safety, but people still seem to be confused. 🤔

In the intricate world of dentistry, where precision is paramount, an often overlooked yet critical aspect is the quality of water used in dental units. Dental unit waterlines (DUWLs), responsible for delivering water to handpieces, air/water syringes, and ultrasonic scalers, have been a subject of concern and discussion within the dental community for years. But despite the waterfall of information from infection control institutions and specialists, confusion around their safe use persists. 


On October 31, 2022, the Centers for Disease Control and Prevention (CDC) released an official health alert underscoring "the importance of following existing recommendations for maintaining and monitoring dental waterlines." This advisory followed the identification of multiple outbreaks of nontuberculous mycobacteria (NTM) in prominent pediatric dental clinics in California and Georgia. 


The root cause of these outbreaks? 

Contaminated dental unit waterlines, resulting in severe infections among young children who had undergone pulpotomies. As you may have already guessed, these clinics had totally neglected the proper treatment and monitoring of their DUWLs. It’s crystal clear at this point that adhering to recommended DUWL guidelines translates into a reduced risk of infection transmission to patients and improved overall clinical efficiency. 


So, let’s delve into the significance of dental unit waterline management, the biofilm lurking within, and best practices for ensuring the best possible dental water quality.


What Is Biofilm? 

Biofilm is a thin, slimy film of bacteria that creates a breeding ground for potentially harmful microorganisms. Dental unit waterlines provide an optimal breeding ground for biofilm due to their construction with narrow tubing, low flow rates, susceptibility to stagnation, and the potential for retraction of oral fluids. These waterlines, extending to air/water syringes and handpiece connections, foster the colonization and growth of such microorganisms on their inner surfaces, forming biofilms that pose a threat to both dental healthcare personnel and patients. 


How Does Biofilm Affect Human Health?

The effluent water from the dental unit carries the risk of contamination when planktonic (single free-floating) bacteria or fragments of biofilm detach and enter the water stream. Legionella, Pseudomonas aeruginosa, and nontuberculous mycobacteria are just some of the culprits that can lurk in untreated dental unit water systems. 


The consequences can be dire, with documented cases of postoperative infections and even fatalities in Italy and Sweden linked to contaminated dental water. Hence, the United States Food and Drug Administration (FDA) recognizes DUWLs as Class I regulated medical devices and mandates their routine cleaning and disinfection.


Dental Water Quality Standards

To combat the risk of microbial contamination, both the Organization for Safety, Asepsis, and Prevention (OSAP) and the CDC have laid down comprehensive guidelines for colony-forming units (CFU) and acceptable levels of biofilm formation. According to the CDC’s 2003 Guidelines for Infection Control in Dental Health-Care Settings, outgoing dental unit water for nonsurgical procedures should have bacterial counts "as low as reasonably achievable," meeting the EPA drinking water standard of less than 500 CFU per milliliter. This was further highlighted in their 2016 Summary of Infection Prevention Practices in Dental Settings. In extreme cases, a boil-water advisory may be issued, necessitating specific protocols to ensure patient safety, including the use of bottled or distilled water for various dental procedures. Regular maintenance of anti-retraction mechanisms is also advised.


The OSAP's Dental Unit Water Quality Whitepaper from 2018 serves as a blueprint for maintaining water quality, emphasizing the importance of performing testing at least monthly on each dental unit using laboratory services and in-office chairside kits. In alignment with these guidelines, the OSAP recommends that stakeholders not only meet but exceed CDC recommendations to achieve the lowest contamination levels. The less than 500 CFU/mL serves as an "action limit," signaling a need for prompt action to improve DUWL quality. It’s good to remember that while it's impossible to eliminate biofilms in dental unit waterlines entirely, you want to maintain a CFU/mL count between 0 and 100 to ensure effective biofilm control. 


DUWL Infection Control Basics

Establishing Standard Operating Procedures (SOPs) and designating an Infection Control Coordinator (ICC) responsible for waterline safety is the first step to efficient implementation of the above-mentioned guidelines. Written protocols ensure a consistent process for waterline maintenance, including guidelines for managing test results and implementing treatment procedures. Clear documentation is also crucial for compliance with OSHA, the Department of Health, and the Dental Board, especially in the event of complaints. 


Do you have written protocols for your waterlines?

If not, my ICC Guidebook has them for you!


Furthermore, OSAP and the CDC recommend having an Infection Control/Prevention Coordinator to oversee procedural water quality testing records, ensuring transparency and compliance when needed. A designated ICC helps establish and maintain best practices, including flushing protocols, the use of antimicrobial agents, and rigorous monitoring and testing procedures. 


Does your dental office have an ICC?

Check out my courses to train one!

Best Practices for Maintaining Clean Dental Unit Waterlines

You can incorporate some practical infection control measures into your daily dental office today to ensure the cleanliness of your dental unit waterlines, such as:

  • Reach out to your dental unit manufacturer for guidance on keeping the water quality top-notch. You've got options like self-contained water systems with chemical treatments, specialized systems for individual chairs or entire practices that clean incoming water, or a mix of these methods.

  • For regular dental treatments, ensure the water you're using meets the standards set by the EPA — it should have less than 500 CFU per milliliter of heterotrophic water bacteria.

  • Avoid using warm water during treatment, as it may promote bacterial colonization and compromise the waterlines. Waterline heaters are not recommended for regular patient treatment.

  • Always flush the DUWLs for 20–30 seconds at the beginning and the end of the day and between patients to maintain optimal cleanliness.

  • Address bacterial accumulation by terminating any unused waterlines, often known as dead legs, as part of your water management protocol.

  • When it comes to keeping your waterlines in check, various products are available — tablets, continuous-release straws, cartridges, shock treatments, and centralized systems. Always make sure to follow the manufacturer's instructions on how to use and maintain them.

  • Use sterile saline or sterile water as a coolant or irrigant for surgical procedures. Regular dental units might not reliably deliver sterile water, even with low-microbial reservoirs, so opt for delivery devices like bulb syringes, sterile, single-use disposables, or sterile water delivery systems that bypass the dental unit.

  • When handling nonsurgical pulpal and endodontic procedures, consider using sterile irrigants or antimicrobial solutions for an extra layer of precaution.

  • Conduct testing on each dental unit after the installation of new equipment, the implementation of new water treatment protocols, prolonged periods of disuse or inadequate maintenance, changes to the manufacturer's instructions, and after maintenance/repairs to the unit.


As always, ensure routine monitoring and treatment of DUWLs when indicated to keep bacterial levels in check. Consistent vigilance is key to maintaining a safe and hygienic dental environment.


How Clean Are Your Dental Unit Waterlines?

OSAP urges dental professionals to stay updated on current recommendations regarding water usage for dental treatment and controlling microbial biofilm contamination in dental unit waterlines. Put simply, you’ve got to stay informed. In this day and age, you can even partner with a dental water lab to access the latest testing, treatment, and shocking options for maintaining optimal water quality in your office. I’d recommend collaborating with an infection control consultant to help you stay current with continuing education courses and routinely test your waterlines. 


Don’t have one in mind? 


Ultimately, clarity around dental unit waterlines is essential for the safety of both dental healthcare staff and patients. As dental professionals, prioritizing patient safety through meticulous waterline maintenance is not just a best practice; it's a commitment to excellence and a crucial element of a thriving dental clinic. 


Let’s navigate these waters with precision and care, ensuring that the flow is not just clear but also infection-free.

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