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Dental Waterlines: CDC Compliance & Protecting Your Practice

Dental Waterlines: CDC Compliance & Protecting Your Practice

Safe Waterlines: Achieving CDC Compliance and Protecting Your Practice

Safe Waterlines: Achieving CDC Compliance and Protecting Your Practice

March 8, 2022

An eight-year-old girl saw her dentist for a routine pulpotomy. A month later, she experienced a severe oral infection, requiring surgery on her jaw and removal of several teeth. She spent a month in the hospital recovering. The suspected cause: Bacteria growth in the dental unit waterline. Infections and mycobacterium abscesses like this are on the rise, and the majority of these cases require hospitalization. Many of these have led to lawsuits against dental practices.

The good news is that these cases are 100% preventable.

Keeping your practice safe

When it comes to protective measures in dental practices, there has naturally been much focus on gear such as masks and shields. However, one area that is not so visible that can cause a great deal of harm is waterline contamination. Microorganisms can grow inside waterline tubing of dental handpieces, air-water syringes and ultrasonic scalers. Ensuring waterline safety measures in compliance with U.S. Centers for Disease Control and Prevention (CDC) guidelines is a critical step for protecting your patients and your practice.

How bacteria grows

The unique nature of dental unit waterlines is a breeding ground for biofilm development, which leads to pathogenic bacteria. Even in the busiest hygiene offices, the water in these super small lines remain stagnant roughly 23 hours a day. Though water may look clear to the naked eye, bacteria can be growing at an alarming rate. This can even occur with new equipment.

A study published in Applied and Environmental Microbiology showed bacteria reaching 200,000 colony-forming units (CFUs) — 400 times the CDC standard — in less than five days using sterile water and brand-new waterlines. Dental practitioners report that they have seen similar results in their labs, with samples that looked clear showing more than 90,000 CFUs of bacteria.

Complying with CDC guidelines

The light blue in the above chart reflects state dental boards that require CDC compliance. If your practice is in one of those states, your license is on the line if you don’t comply. In Washington state, additional regulations began in December 2021, requiring quarterly waterline testing. Regardless of whether you’re in a state that requires CDC compliance or not, it’s very important to treat each waterline product following the manufacturer’s instructions. This is for your own safety, as well as the safety of your practice, your patients and your co-workers. Case in point: an oral surgeon in New Jersey had 15 patients who contracted endocarditis from infection control breaches — including not using sterile water from a sterile delivery system. One patient died as a result.

Setting up an effective waterline maintenance protocol

For every instrument that puts water into a patient’s mouth, the CDC recommends following three steps:

Step 1: If you’re performing any type of surgical procedure (e.g., involving a scalpel or a suture), you need to provide sterile water from a sterile delivery system. This doesn’t mean opening up a bottle of sterile water and pouring it into your regular dental units; if you do so, it will no longer be sterile. You either need a surgical pump piece or a Monoject™ syringe with saline to deliver the sterile water or saline from a sterile device.

Use a strong chemical to shock and clean out the inside of the lines, because you can’t get in there with a brush to clean them up. The product line Liquid Ultra™ or a diluted bleach solution will do the trick. According to CDC guidelines, systems should have a two-minute flush in the morning and a 20- to 30-second flush in between patients (Do not put waterline shock into evacuation or suction lines, as those have their own shock products).

Note: If you're using a straw, you still need to shock. Never shock through a straw, however, as it will ruin the effectiveness of the straw. If you’re using a straw product such as DentaPure™, Sterisil® or BlueTube®, you can use a dummy straw to lengthen the straw and shock the lines.

Protect your lines further with daily water treatments. This goes hand in hand with shocking.

Step 2: Test and monitor dental unit water regularly. Most dental equipment manufacturers, such as A-dec®, Pelton and Crane, Midmark® and DENTALEZ®, now recommend testing quarterly or monthly. The gold standard is the R2A test method. You can also use a testing method called Flo, which delivers same-day results, so you can quickly know if corrective action is needed.

Step 3: Verify compliance by documenting the steps you took to comply, and test the results. Water needs to meet the U.S. Environmental Protection Agency (EPA) standard of 500 CFUs or less per milliliter of colony-forming Heterotrophic bacteria.

Municipal water supplies and centralized systems

If your dental units are connected to a municipal water supply and you don’t have water bottles, you can retrofit your system inexpensively to shock your waterlines. Some practitioners believe that having a centralized system will take care of sanitation needs; however, this is no magic bullet. Having a centralized system doesn’t negate the requirements for shocking. The systems routinely need to be sanitized and filters need to be replaced.

Sanitation methods

In the largest treatment efficacy study ever conducted, ProEdge Dental Water labs collected data from more than 22,000 consecutive water tests, which revealed that more than 31% of treated unit waterlines failed. One of the key pieces of data from the study, compiled by John Molinari and Nancy Dewhirst, was that tablets with a shock passed almost 90% of the time. The study data further showed that government facilities and community health clinics that require quarterly testing passed 95% of the time. The vast majority use the above-mentioned three-step protocol. Dental service organizations and general practices — who generally aren’t aware of the same requirements in terms of testing — pass 70% of the time.


Waterline requirements are updated periodically. Following the latest guidance is a critical way to not only ensure CDC compliance but to keep patients safe. This also protects your practice from the inherent risks of infections.

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