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Don’t bury your waterlines in the sand: The importance of DUWL maintenance

June 10, 2020
No matter how hard you tried to dry your office's waterlines before you closed, they will need attention when you reopen. Here's why.

Ostriches may have the right idea. When life gets overwhelming, they bury their heads in the sand. With all the swirling questions and unknowns in the dental industry right now, I’m tempted to do the same. How will we get the PPE we need, or better yet, what is the PPE we need? Will I ever touch my Cavitron again? When will we be back in the op? Will it be safe? What will I need to wear? How long will all this last? It’s all very overwhelming, and misinformation is rampant. Actually, the ostrich thing isn’t even true—see? More misinformation! Ostriches bury their eggs in the sand; humans just observed them digging, misunderstood the behavior, and widely circulated the myth that ostriches bury their heads in the sand. What information can you trust anymore?

I guess if the ostriches aren’t hiding, we can’t either. Rather than focus on the unknowns, now is an excellent time to focus on what we do know. Let’s dig into tasks we can be doing. The OSAP-DALE Foundation recently offered their infection control certificate for 50% off, and many took advantage of this time off to become infection control experts. While much of the information is stuff we should know, there is a lot to be said for brushing up on all the “should”s before we tackle more “to do”s. We’d be hard pressed to find an office that is doing all of the “should”s all of the time.

As we head back into the operatory, there is a list of tasks and policies that need to be put into place to protect our team and patients and ease palpable fears. Much of this will be highly visible—taking temperatures, administering questionnaires, wearing new PPE, but what about the tasks that no one sees? For example, have you thought about your dental unit waterlines (DUWLs) while you’ve been home racking up CEUs and bingeing on Netflix? One thing is for certain, the biofilm has been having a COVID-19 party in your tiny, damp waterlines, no matter how hard you tried to dry them out before closing the office.

Aside from DUWL maintenance being on the list of “should”s regarding infection control, people have actually gotten sick or even died from the biofilm in DUWLs. There is a case due in court—whenever court reopens—in Anaheim, California,1 where over 150 patients required hospitalization and surgery after receiving treatment at the same office. When officials tested their DUWLs, five waterline samples came back with mycobacterium abscessus. The most fascinating part about this story is that the onset of symptoms ranged from 1-409 days later. There’s another case in New Jersey2 and yet another in Atlanta, Georgia,3 waiting to come to trial. This is a big deal.

So yes, it does amount to one more thing to do. But the stories above really drive home how important it is to tend to DUWLs. The good news is this is a doable process and, truthfully, kind of fun! While each office must have a designated infection control officer, that does not mean that person has to take on every task. It’s simply their job to ensure all the “should”s are getting done. Delegate a waterline officer. Titles are fun and help make each person feel like a valued part of the team. Simply follow the four-step process below to make sure your waterlines are safe.

1. Shock

First you have to shock all DUWLs. When I say all, I mean all. Even the ones you don’t use—especially the ones you don’t use—they are the most likely to have built-up biofilm due to stagnancy. To shock, you can use a diluted bleach solution or a prepared shock solution. There are many articles and videos online for exact instructions on how to shock based on the method you choose and your unit manufacturer’s recommendations. (Do not shock your lines with an antimicrobial straw in place. Be sure to install a dummy straw or you risk ruining your straw.)

2. Test

Next, you need to determine if your lines contain less than 500 colony forming units (CFUs). There are a few options out there for testing. You can do it yourself with an in-office test such as ProEdge Dental’s QuickPass or an Aquasafe Water Test Kit. They are both easy to use. The QuickPass has a 48-72-hour incubation period, while the Aquasafe kit requires seven days. Alternatively, you can outsource and send samples to a lab. Once again, when you test, make sure to test all of your lines. That could mean water samples from three to seven lines per operatory; don’t forget your ultrasonic scaler, it has a waterline, too. The good news is that studies are showing a pooled sample is acceptable. This means that you can use one test vial per operatory, just fill your receptacle with equal amounts of water from each line you’re testing. If your lines don’t pass the test, go back to step one and shock again, perhaps with a different solution.

3. Treat

Now that you have determined your lines are safe, focus on keeping them that way. Select a continuous waterline treatment like BluTab, or you can install a straw into your unit water reservoir that is replaced yearly. Don’t be fooled by a well-meaning rep that tells you the tabs or straw are all you need to do. Unfortunately, even the best products fail, but it helps when you are following the instructions for use (IFU) closely. Each product has different IFU and has been tested and retested to work when you follow their instructions. Some instruct you to leave the bottle full at night, some say to empty it, some require distilled water, others might say don’t. Just because the office down the street is doing it one way doesn’t mean it’s the right procedure for your office. Here’s an example of a daily waterline routine using BluTab:


  • Top off the unit reservoir bottle with prepared BluTab solution. (Take a clean container and fill it with two liters of water, put in three 750 mL tabs or one 2 L tablet.) Reattach the water bottle.
  • Turn the unit on.
  • Run all lines for two minutes.

Between patients

  • Run all lines that enter the patient’s mouth for 20-30 seconds.


  • Run lines for two minutes to ensure treated water will remain in lines overnight.
  • Turn the unit off.

If your ultrasonic scaler has a separate water source, be sure to complete all steps above with it.

4. Retest

Retesting waterlines is key to ensure that regrowth has not occurred. OSAP recommends5 retesting monthly at the beginning of implementing your waterline maintenance routine. If monitoring results show your water quality is acceptable for two consecutive months, you can move to quarterly testing. If a unit fails, you restart the cycle from step one and shock your lines.

Be sure you’re keeping accurate records of your efforts. Dental Board inspectors are consistently asking for this documentation to ensure compliance. ProEdge has a free checklist you can download or feel free to create your own, what matters is that you’re keeping track. Also consider ways of letting patients know all you are doing to keep their visit safe. It’s okay to brag about your passing test scores.

All that said, if you fail, don’t despair. This process isn’t shock once, maintain and you’re good for eternity. Biofilm builds up fast and sometimes the maintenance treatment can’t keep up, which is why it’s key to retest. If you fail, simply start back at step one. Think of DUWL maintenance the same way we think of our patients’ dental care: That SRP isn’t the end, it’s the beginning of a long line of perio maintenance appointments.

Stop fantasizing about burying your head in the sand and schedule three-month appointments with your DUWLs; it’s a small-but-vital check on the to-do list for office safety.


  1. Singh J, O’Donnell K, Ashouri N, et al. 926. Outbreak of invasive nontuberculous mycobacterium (NTM) infections associated with a pediatric dental practice. Open Forum Infect Dis. 2018;5(suppl 1):S29. doi:10.1093/ofid/ofy209.067
  2. Associated Press. Dentist agrees to suspension after 15 patients sickened. ABC News. Published February 4, 2020. Accessed May 29, 2020. https://abcnews.go.com/Health/wireStory/dentist-agrees-suspension-15-patients-sickened-68745756

  3. Peralta G, Tobin-D’Angelo M, Parham A, et al. Notes from the Field. Mycobacterium abscessus Infections Among Patients of a Pediatric Dentistry Practice—Georgia, 2015. MMWR Morb Mortal Wkly Rep. 2016;65(13):355-356. doi:10.15585/mmwr.mm6513a5 

  4. Bleach shocking guide. Patterson Dental. Accessed May 29, 2020. https://content.pattersondental.com/items/PDFs/images/PDF_629069.pdf

  5. Mills S, Porteous N, Zawada J. Dental Unit Water Quality: Organization for Safety, Asepsis and Prevention White Paper and Recommendations–2018. J Dent Infec Contr Saf. 2018;1(1):1-27. https://osapjdics.scholasticahq.com/article/5075-dental-unit-water-quality-organization-for-safety-asepsis-and-prevention-white-paper-and-recommendations-2018

Amanda Hill, BSDH, RDH, has been in dentistry for over 25 years. She currently practices part-time clinically and is an industry educator for DentalPost.net. Hill recently began writing for dental publications as a way to share her passions. Additionally, she’s a member of the advisory board for RDH magazine and hosts her very own podcast on the Dental Podcast Network, Your Dental Top 5. Amanda is a proud Navy spouse and mom of three, and is intent on spreading kindness wherever she goes.

About the Author

Amanda Hill, BSDH, RDH, CDIPC

Amanda Hill, BSDH, RDH, CDIPC, is an enthusiastic speaker, innovative consultant, and award-winning author who brings over 25 years of clinical dental hygiene and education to dentistry. Recipient of ADS’s Emerging Infection Control Leader award and an active participant with the advisory board for RDH magazine, DentistryIQ, and ADS’s Infection Control in Practice Editorial Review Board and membership committee, Amanda (also known as the Waterline Warrior) strives to make topics in dentistry accurate, accessible, and fun. She can be reached at [email protected].