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The DIY assistant: Waterline maintenance

July 20, 2021
Keeping the waterlines clean and flushed is among your most important jobs. Here's how to make sure you're doing it properly.

Waterline maintenance is something dental professionals don’t talk about much, yet it’s one of the most important things dental assistants do. It’s a huge part of our infection control responsibilities, and it’s important to know how to test and shock the waterlines the correct way.

I remember when I was a young assistant, we didn’t test our autoclaves but simply assumed that they worked. When we began testing, we realized we had a big problem. Our dental unit waterlines (DUWL) are much the same. We don’t know if our water is acceptable unless we test it. Clean water going into our lines doesn’t mean there’s clean water at the other end. As a matter of fact, it’s quite the opposite. You see, the lines themselves are where the problems begin, from the amounts of bacteria accumulating in them, to the types of bacteria that grow in the lines. It’s a crazy breeding ground for some nasty germs that can cause serious illnesses for our patients.

Let’s discuss some of the bacteria that live in our lines. It’s called biofilm, and think of biofilm like plaque on the teeth—if you don’t brush for a day, it accumulates, and if you don’t brush for two or three days, it builds up even more. Bacteria such as Legionella, Pseudomonas aeruginosa, and Mycobacterium all cause disease, and our waterlines are the perfect places for them to live and flourish.

What harm does bacteria do? Serious illnesses have been reported in the US and linked back to dental offices, affecting several patients in each case. Most notable are the cases in Anaheim, California, and Jonesboro, Georgia. In these cases, children were infected when the waterline bacterial count reached unacceptable levels, resulting in more than 100 children becoming ill and causing millions of dollars in damages. A patient in Rome died due to an infection caused by dental unit waterline contamination. Bacteria can also cause issues with healing after periodontal surgeries.

What is considered clean water? The American Water Works Association (AWWA), the Environmental Protection Agency (EPA), and the American Public Health Association (APHA) established some guidelines. The Centers for Disease Control and Prevention (CDC), the Organization for Safety, Asepsis and Prevention (OSAP), and the American Dental Association (ADA) agree with them that 500 colony forming units per milliliter (500 CFU/ml) or less of heterotrophic bacteria is safe for consumption. It shouldn’t come as a surprise that approximately one third of first-time waterline testers fail with bacterial counts that are well into the thousands.

Stagnation, which is the slow flow rate of the water, as well as the fact that some units can go hours or even days without being used, is of concern and can lead to these high numbers. The water becomes stagnate, which gives bacteria a perfect place to breed. This means that treating the water at the source (self-contained water bottle) is extremely important and just the beginning of a maintenance program.

How to properly maintain DUWLs

Purge your lines: A recommendation from the CDC is to purge your lines by running them for two minutes at the beginning of each day. This flushes out the stagnate water that sat all night. You also want to do this for at least 20 seconds in between patients to prevent the introduction of patient material into the lines.

Treat your water: It’s important to have a daily routine to treat the water used in your lines. It’s preferred to use the best source water as possible, but to also treat it to keep levels low. There are several products on the market that are easy to use. Just be sure to follow the manufacturer’s instructions for use (IFU) because they may differ.

Test your water: How do you know if your water is clean unless you test it? The answer is: you don’t know! The CDC recommends testing your water once a quarter and making it part of your maintenance schedule. Test kits are either in-office, which can be done by any team member, or mail-in. There are benefits to both methods, and you may choose to use each at different times.

Shock your water: It’s important to always test first. Shocking your lines to kill any bacteria accumulated is essential to keep your patients safe. The CDC recommends shocking your lines once a quarter, after you test your lines. Make sure the product you are using says “shock” and it’s not just a treatment. This is a mistake that a lot of offices make when maintaining their lines. Shock products differ greatly, so be sure to read and follow the IFUs for all products.

Tija Hunter, CDA, EFDA, CDIA, CDSH, CDSO, MADAA, is a member and current vice president of the American Dental Assistants Association (ADAA), where she holds the honor of Master. Hunter is the editor of Dental Assisting Digest and contributes to Dental Economics magazine. She is the director of the Dental Careers Institute, a dental assisting and dental continuing education program, and an international speaker and certified trainer in nitrous oxide in several states.