This testing site maintained seven 20 year old adec dental units. All dental equipment prior to the employment of the Waterclave system had no attempts to correct the biofilm levels. The CFUs/ml level reached the testing cap of < 30,000 CFUs/ml on every sampled port. An initial chemical flush was introduced for overnight treatment and the following treatment day the Waterclave unit was functional. Testing was performed at 10 days post chemical flush followed by monthly testing of all treated waterline ports by an independent lab. Not until the 100th day did a resurgence of the bacterial numbers occur. All dental units were retreated with an overnight chemical flush and the lines maintained their 0 CFUs/ml over 4 months.