Waterline Safety - AMANDA HILL, RDH, BSDH

Waterline Safety - AMANDA HILL, RDH, BSDH


Amanda Hill RDH, BSDH has been a dental hygienist for over 26 years. When she took her annual infection control training in 2017, the speaker covered waterlines. She never knew that she had to do more than flush her waterlines. No one else in her dental office knew that they were supposed to do more.


Her practice failed their first water test, badly. So Amanda dug in and got them to pass their water testing. Then she started offering to help other dental offices. In this episode, Amanda shares her expertise and we have a deep discussion about waterline testing. 

Outline of This Episode

  • [1:56] Learn more about Amanda Hill AKA the “Waterline Warrior”
  • [6:24] Open line versus closed waterline systems
  • [11:10] What is a biofilm and how do you kill it? 
  • [16:08] Amanda’s favorite germicide delivery system
  • [19:39] Reasons you need to do waterline testing
  • [26:25] Why you want to be consistent with treatments
  • [28:40] How frequently you should test your waterlines
  • [33:24] Addressing the flushing your waterlines debate
  • [38:33] Waterline testing must include documentation  

Open versus closed waterline systems

Where does your water come from? The city pipes? Does that water flow into your handpiece, cavitron, air polisher, and air water syringe? Or do you have a bottle you fill and use every day, i.e. a closed system? 


When you use an open system, you lose control over your water. Can you shock or treat your lines if your water is coming from the city? The answer is no.


With a closed bottle system, you can add a tablet, liquid, or straw germicide to maintain your line. If your water fails, you can shock the lines without calling a service tech or installing special filters. A closed bottle system gives you control. 


The water that comes from your sink faucets is usually safe to drink (which means there are less than 500 colony-forming units detected in the water). Why are dental unit waterlines problematic? The small tubing and low flow rate you use allow biofilms to form.

What is a biofilm and how do you kill it? 

A biofilm is bacteria, viruses, and fungal colonies that form and grow. They adhere to waterlines and continue to build. Legionella, Pseudonymous, and Mycobacterium can commonly form in waterlines and cause patient illnesses. 


So how do we kill biofilms? Germicides. There are liquids and tablets that can effectively kill the colonies (if you follow the instructions correctly). However, at some point, they can become ineffective. That’s why you must routinely test your waterlines. 


You maintain your waterlines with a germicide liquid, tablet, straw, etc. to keep the biofilm at bay and shock the lines. If a certain treatment becomes ineffective, you can switch to a new one and test your lines routinely until you pass.

Reasons you need to do waterline testing

Why do you need to routinely test your waterlines? Firstly, you need to know that your treatments are working. And what if the CDC or FDA knocks on your door and asks you for your test results?


Infection control isn’t just about covering your butt so you don’t get sued. It’s about taking care of your team and your patients. Ohio State University conducted a study where they captured the aerosols in an operatory. 78% of the aerosols came from the waterlines. 


What are you breathing in all day long that could be coming from your waterlines? You need to make sure your team and patients stay healthy. 

How frequently should you test your waterlines?

Amanda emphasizes that you should test your waterlines monthly until you pass for three consecutive months (OSAP’s recommendation). You want to make sure the biofilm doesn’t grow back. At that point, Amanda notes that you can test your waterlines quarterly. If you fail your test, go back to monthly testing and if possible, you can test weekly (Amanda’s preference). 


When you test your waterlines and pass the tests, tell your patients. Blast it on social media. Dental offices aren’t required to test their waterlines—but they should be. Your patients need to know that you’re doing everything possible to keep them safe. 

When should you test your waterlines more frequently? Listen to find out! 

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