Don't miss a digital issue! Renew/subscribe for FREE today.
Inside Dental Hygiene
April 2022

Waterline Integrity

Ensuring DUWL infection control

Jamie Collins, RDH-EA, BS

Dental unit waterlines (DUWLs) are one of the most critical components in any dental office. When you don't have water, most dental procedures must come to a halt. DUWLs are also one of the most overlooked aspects of dentistry, and team members often disagree about proper care. The treatment and maintenance of DUWLs has adapted with technology over the years, as have many of our infection control protocols. When it comes to maintaining the integrity of the waterlines, many dental professionals learn from another, read an article, or assume they know the proper care. Ask yourself how effective your DUWL infection control procedures are, and are you doing enough?

When patients walk into the office, they gaze around and make a determination on the cleanliness and infection control within seconds. What they don't see is the "dirty" and silent secret that lurks in the DUWLs of many practices. In fact, nearly one third of water testing fails to meet the CDC and EPA standard of less than 500 colony forming units of heterotrophic bacteria per milliliter (≤ 500 CFU/mL) of water.1 The breeding ground in an untreated DUWL can lead to levels that exceed 200 to 400 times the recommended standard.

Proper maintenance protocol can prohibit the growth of potential harmful bacteria, protozoa, fungi, and more, including Legionella, which can contribute to severe pneumonia and lung inflammation. Streptococcus and Staphylococcus are two very common bacteria forms that thrive in aquatic environments, including dental unit waterlines. An immunocompromised patient may be at high risk of severe infection because of improperly maintained water lines.

Determining the Right Approach

With misinformation on the internet and differences in opinions, it is important to research the best way to maintain your particular unit. To prevent damage to the unit, the first step is to consult the manufacturer's directions, as some units require a different approach to maintenance than others. All dental workers should be educated on the correct methods of DUWL care and maintenance, regardless of their personal opinions and perceived knowledge. A schedule for care must be established and adhered to as part of the infection control protocol. Just as wearing a mask, gloves, and other personal protective equipment (PPE) is required, all infection control safeguards must be followed.

Safety First

In general, the addition of anti-retraction devices on all units is recommended to prevent a backflow of fluids from the patient. The use of a bottle system on each unit, rather than municipal water, helps ensure the quality of the water source. Directly connected water treatment systems are convenient and effective, however the upfront cost can be daunting. Avoid using warm water in the unit, as it has been shown to increase microorganism growth; safety outweighs convenience.

Begin and end the day by flushing the waterlines for several minutes to expel any stagnant water. The CDC, OSAP, and ADA all recommend running the DUWLs for 20-30 seconds between each patient and immediately attaching a sterilized handpiece, air-water syringe, ultrasonic insert, or other equipment to prevent cross contamination.

All surgical procedures should be completed with sterile water only, rather than municipal or bottle source, to prevent water borne infections. Successful outcomes may be dependent on multiple factors, so clinicians should ensure they have done everything possible for the safety and well-being of the patients.

Test Often

It is important to test your DUWLs frequently to ensure your protocol is effective. Initial testing should be conducted monthly until multiple acceptable tests are confirmed. Then the testing may be indicated quarterly. Advances over the years have provided multiple testing options, including in-office and mail-in testing. Collection of water samples and a mail-in service such as ProEdge Dental Unit Waterline Testing Kit (ProEdge Dental Water Labs), StandardCheck (Sterisil, Inc.), or R2A Spreadplate Method (Agenics Labs) will yield results in a matter of days.

Unit Maintenance

To shock or not to shock? With many choices on the market and different recommendations based on the dental unit, it can be daunting to determine a protocol and product—whether a tablet, liquid, or filter. When DUWL tests exceed the recommended 500 CFU/mL of heterotrophic water, a shock treatment is required to reduce the bacteria present and decontaminate the waterlines. There are choices in products, and once again the manufacturer of the unit should be consulted, as some treatments require overnight while others may require three days in the lines.

Maintenance is key with all equipment, and DUWLs are no exception. If proper maintenance is not performed through the use of filters, shock treatments, and daily and weekly care, you may be putting your patients at risk. Choices range from daily maintenance tablets added to each bottle of liquid filled to weekly maintenance liquids, some of which will perform a shock and maintenance all-in-one, making it a convenient end-of-the-week routine. Options include Monarch Lines Cleaner (Air Techniques) and MicroCLEAR (Rowpar Pharmaceuticals).

The most important element when creating a DUWL protocol is adherence. Even the best of plans will all fail and allow the biofilm to creep in if the schedule is not maintained. More important than the product used is the implementation of the program. Test monthly or quarterly depending on previous test results and maintain the records of test results and system maintenance. Daily or weekly maintenance as determined by the DUWL manufacturer and infection control procedure manager must be communicated to all current and new dental team members. Infection control, prevention, and protections continue to evolve, and non-visible protections should still be cutting edge.

About the Author

Jamie Collins, RDH-EA, BS
Clinical Practicing Hygienist Educator and Key Opinion Leader
Idaho and Washington state


1. Birschbach K. The comprehensive dental water testing guide. ProEdge Dental Water Labs website. Published March 19, 2019. Accessed March 1, 2022.

© 2024 BroadcastMed LLC | Privacy Policy