Dental Unit Waterlines: A Survey of Practices in Eastern France. 
Water is essential during dental care.  Physical and chemical techniques should be used to maintain a good water quality with respect to bacteria, and to ensure the safety of exposed patients and dental staff.  The aim of this survey was to assess the modalities used by dental practitioners in Eastern France to maintain the water quality of their dental unit waterlines (DUWLs).  A questionnaire about water quality maintenance practices was sent to 870 dental offices in 2016.  The questionnaires were completed by 153 dental offices, covering about 223 dental care units.  The majority of units were fed by mains water (91.0%), which is generally unfiltered (71.3%).  One-third (33.6%) of the units had an independent water bottle reservoir.  Flushing, a basic physical technique to improve the quality of units' outflow water, was practiced in 65.4% of dental offices.  Concerning the chemical treatment of water, it was used for 62.1% of the units.  An analysis of the microbiological quality of the DUWL water was only carried out in 2.6% of the offices.  In conclusion, providing better training to dental staff seems necessary to improve their practices and to generalize procedures that improve the microbiological quality of the water used.