Since 2003, the Centers for Disease Control and Prevention (CDC) has published comprehensive guidelines for dental water infection prevention. With well-established scientific basis, these guidelines have been supported by the American Dental Association (ADA), U.S. Food and Drug Administration (FDA) and Organization for Safety, Asepsis and Prevention (OSAP), as well as nearly 80% of dental boards across the United States.

As supporters of patient safety within the dental practice, dental assistants who have a complete understanding of these recommendations can be the difference between your practice operating with high standards or it operating with those standards compromised.



The CDC’s Guidelines for Infection Control in Dental Health-Care Settings – 2003 has four key recommendations for practices when it comes to dental water safety:

Key Recommendations for DENTAL UNIT WATER QUALITY in Dental Settings

  1. Use water that meets EPA regulatory standards for drinking water (i.e., ≤ 500 CFU/mL of heterotrophic water bacteria) for routine dental treatment output water.
  2. Consult with the dental unit manufacturer for appropriate methods and equipment to maintain the quality of dental water.
  3. Follow recommendations for monitoring water quality provided by the manufacturer of the unit or waterline treatment product.
  4. Use sterile saline or sterile water as a coolant/irrigant when performing surgical procedures.
Source: United States Centers for Disease Control; Infection Prevention and Control in Dental Settings; Summary of Infection Prevention Practices in Dental Settings; “Dental Unit Water Quality”; June 18, 2018.


However, it can be helpful to divide these into three pillars.

1. Surgical Water

For all surgical procedures, which the ADA defines as “those that involve the incision, excision, or reflection of tissue that exposes normally sterile areas of the oral cavity,” sterile water and sterile water-delivery systems are required.

Confirmed by the ADA, using sterile water within dental units is not adequate. As soon as sterile water enters a dental unit, it is highly likely to be contaminated. Both sterile water and sterile water-delivery systems (such as a sterile bulb syringe or single-use disposable products) need to be used for every surgical procedure.

2. Dental Unit Water

For all other procedures, dental unit water should meet or exceed the U.S. Environmental Protection Agency (EPA) standard for safe drinking water of ≤500 colony forming units (CFU) per milliliter (mL) of heterotrophic water bacteria. While the CDC identifies a handful of proven strategies to consistently reach this threshold, a dental practice may utilize all or a combination of these strategies.

Research shows that untreated dental unit waterlines with chemical germicides are unlikely to remain clean. In fact, a study found that even in brand-new waterlines, contamination upwards of 200,000 CFU/mL can develop in less than five days.

Regardless of the treatment protocol chosen, the ≤500 CFU/mL standard should be met.

3. Verification of Compliance

The next question is, how do you know if your treatment is meeting the ≤500 CFU/mL standard?

It’s a great question.

A study cited in the peer-reviewed article “Treating and Monitoring Dental Water Quality” by John A. Molinari, Ph.D., and Nancy Dewhirst, RDH, B.S., revealed that 31% of treated waterlines still failed to meet the ≤500 CFU/mL standard, and some treatment solutions performed significantly worse.

While treatment of dental unit waterlines is a vital aspect of dental water safety, it alone is not a guarantee. Waterlines must be tested regularly to ensure an effective protocol.

Additionally, testing demonstrates compliance with documentation. That documentation is your practice’s protection should there ever be an inspection, a complaint or an infection. To prove compliance, practices should keep documentation and records of standard operating procedures (SOPs), team training/education and waterline test results proving their protocol has been effective.



The CDC, ADA, FDA and OSAP recommend testing as frequently as your dental unit and treatment product manufacturer recommend.

If no frequency recommendations exist, or are unclear, OSAP’s 2018 recommendations state that practices should monitor water quality “at least monthly on each dental unit or device … If monitoring results indicate that water quality is acceptable for two consecutive monthly cycles, the frequency of testing may be reduced, but should not be less than every three months (p. 11, 17).”

For you, it is about making sure every patient gets the best care. For your practice, it’s about making sure the practice complies with industry standards.

Too many practices have been in the headlines in recent years for breaches or, worse, infections. Make sure your practice is in compliance with these three pillars to help ensure the safety of your patients and practice.

This blog post is sponsored by ProEdge. DANB and the DALE Foundation have not evaluated the statements made in this post.