Adams School of Dentistry: Infection Control Manual - Chapter 09: Dental Unit Waterlines (DUWL) & Vacuum Maintenance

General Dental Unit Water Lines Information on Water Quality

Dental unit waterlines (DUWL) are susceptible to the growth of biofilms (sticky, slimy bacteria that sticks to moist surfaces) due to the small diameter of the tubing, low fluid flow rates, potential for fluid retraction, and frequent periods of stagnant water retained in the tubing. Consequently, common water bacteria that can be disease-causing such as Legionella, Pseudomonas aeruginosa, and nontuberculous Mycobacterium can be found in high numbers in untreated dental unit output. Waterline maintenance requires a combination of necessary steps to prevent buildup of biofilm and a system of monitoring water quality with quantitate measurements of heterotrophic bacteria.

Current guidelines set by the US Environmental Protection Agency require drinking water meet regulatory standards of ≤500 colony forming units (CFU/mL); this requirement is applied to DUWL.

DUWL Maintenance Procedures

One of two preventative treatment systems are utilized in ASOD, either an automated treatment “straw” or manual tablets that are placed each time water is added to the unit. ASOD primarily utilizes the treatment “straw” option for most dental units, due to the use of primarily municipal water sources. SURGICAL PROCEDURES should always utilize sterile water for irrigation, not water from the dental units.

DUWL Maintenance - Treatment Straw & Daily Use

ASOD dental units should all utilize the treatment straw option and are replaced according to manufacturer guidelines, which include but are not limited to, every 90 or 365 days, and should automatically maintain ≤10 CFU/mL. Daily maintenance for all operatories to include the following:

1. Flush waterlines at the start of each day AND for 30 seconds before each patient by dispelling water into a sink, denture cup, vacuum hose, or other appropriate method.
2. Items to flush include, but are not limited to, all handpieces, ultrasonic unit, and air/water syringes.
3. Purging of each above-mentioned area can be completed in one of the following ways:
   • Using the “purge button” on the back of each unit is the preferred method to purge waterlines if it is present.
   • If purge button is not present, handpieces and ultrasonic units can be purged by utilizing the rheostat. Air/water syringes on the operator and assistance side can be purged by depressing the water button.

DUWL Maintenance - Tablet Solution & Daily Use

While not preferred, ASOD dental units can utilize a preventative, proactive tablet solution need to be replenished each time a dental unit water bottle is refilled. Partially filled water bottles require that excess be dumped before adding additional water to the bottle. Follow manufacturer guidelines on use and perform the following daily maintenance for all operatories:

1. Flush waterlines for 30 seconds before each patient by dispelling water into a sink, denture cup, vacuum hose, or other appropriate method.
2. Items to flush include, but are not limited to, all handpieces, ultrasonic unit, and air/water syringes.
3. Purging of each above-mentioned area can be completed in one of the following ways:
   • Using the “purge button” on the back of each unit is the preferred method to purge waterlines if it is present.
   • If purge button is not present, handpieces and ultrasonic units can be purged by utilizing the rheostat. Air/water syringes on the operator and assistance side can be purged by depressing the water button.

DUWL Monitoring

Water quality should be monitored by performing a test that provides a quantitative measurement of heterotrophic bacteria. Testing should occur annually, at a minimum, depending on the test results and water quality goals. DUWL testing is completed through a certified lab and performed on randomly selected dental units, which is overseen by a representative appointed by each division area. Results are reported to the Infection Control Committee to ensure the continued safety of water used in patient care.

Units tested that result in ≤400 CFU/mL must be checked again within 1 month of shocking treatment to verify results, with the process repeated until levels below ≤400 CFU/mL are reached, then may return to the original testing schedule. Units tested that result in ≤500 CFU/mL or higher should be reported to the department chair and Director of Clinical Compliance immediately.

DUWL Shock & Installation - Treatment Straw

Shock treatment clears deposits and bacterial contamination from dental unit waterlines. When treatment straws are installed, the unit has been unused for 14+ days, water source has been compromised, or the DUWL testing indicates a value of ≤400 CFU/mL, the unit must receive a shock treatment by the overseeing division area, department, or certified outside organization. Compromised water includes but are not limited to:

1. water main break that allows contaminants to reach dental units;
2. any time a “boil water alert” has been issued by a local health department; or
3. any situation where obvious contamination of the dental unit has occurred.

Installing new treatment straw

1. Follow manufacturer guidelines on replacement procedures.
2. Don appropriate PPE indicated by manufacturer instructions
3. Appropriate shock treatment will need to be flushed through all waterlines and left overnight or between 12-15 hours, whichever comes first. Amount of time is necessary to effectively disinfect the water lines.
4. Purge each line for a minimum of 60 seconds or until any remaining color from the shock treatment is no longer being expelled, to ensure all shock treatment has been removed.

Unit unused 14+ days or DUWL test higher results ≤400 CFU/mL

1. Gather shock materials, which are not the same shocking material provided by the manufacturer of the treatment straw
2. Follow manufacturer guidelines on replacement procedures
3. Don appropriate PPE indicated by manufacturer instructions
4. If disinfectant spills on a hard surface, dental chair, or other part of dental unit, clean the area with soap and water immediately to avoid equipment damage.
5. Complete BOTH of the following procedures to disinfect and flush DUWL’s, with modifications to procedure allowed per manufacturer guidelines.

DUWL Disinfection Procedure

1. Turn off dental unit.
2. Remove the external water bottle and retrieve a bottle without a treatment straw. Be sure to mark the original bottle so it is returns to the correct unit.
3. Pour disinfectant into the second water bottle, ensuring that disinfectant will not be expelled through any treatment straw, and attach water bottle to unit.
4. Turn the dental unit on and express water from both air/water syringes into an appropriate disposal area until disinfectant is seen being expelled. If utilized a container to catch the expressed water, dispose of it in a sink or HVE.
5. Repeat the above step for all handpiece and ultrasonic lines.
6. Turn off dental unit.
7. Remove water bottle with disinfectant from unit, dispose of any excess material, rinse bottle, and place a patient napkin under the area where a water bottle is normally held. Material may leak slightly and will stain the floor.
8. Leave disinfectant to sit in the waterlines overnight, between 12-15 hours, or according to manufacturer instructions.
9. NOTE: Always follow the manufacturer’s “Instructions for Use” (IFU). IFU’s supersede any procedures or processes currently in place. If this occurs, contact the Director of Clinical Compliance.

Post Disinfection: DUWL Flushing Procedure

1. Fill original bottle with treatment straw from unit with fresh water from filling station.
2. Turn off dental unit if it is not already off.
3. Attach full water bottle to unit and turn dental unit on.
4. Express water from both air/water syringes into an appropriate disposal area until the water runs clear, indicating that all disinfectant has been expelled. If utilized a container to catch the expressed water, dispose of it in a sink or HVE.
5. Repeat the above step for all handpiece and ultrasonic lines.
6. Refill water bottle if appropriate and clean any spilled items; unit is ready for patient care.
7. NOTE: Always follow the manufacturer’s “Instructions for Use” (IFU). IFU’s supersede any procedures or processes currently in place. If this occurs, contact the Director of Clinical Compliance.

Vacuum Lines, Traps, & Vacuum Materials

Vacuum lines should be treated with an US Food and Drug Administration approved disinfectant on a bi-weekly basis or after each surgical procedure, whichever comes first. Traps are removed and either cleaned or disposed of in biohazard bins and replaced, according to manufacturer guidelines, at the end of each week.

Disposable air/water syringe tips, high-volume evacuation (HVE) tips, and saliva ejectors are replaced between each patient or if contaminated (i.e., dropped on the floor). Use of HVE adapters that allow for increased moisture control and single operator procedures that contain a disposable component must be changed between each patient. All equipment certified for reuse and attaches to vacuum lines must be appropriately cleaned, disinfected, and sterilized according to manufacturer instructions before reusing.

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