Drinking water must meet EPA safety standards upon leaving water treatment plants. With aging pipelines, corrosion can cause elevated iron levels in water and increase microbial biofilm build up in pipes. Moreover, water stagnation and narrow tubing waterlines in dental chair units (DCUs) provide conditions suited to biofilm formation which presents a considerable concern for patients and health care workers alike. Finally, clean up of dental instruments used in various filling procedures can discharge mercury in the water effluent. This present study aims at analyzing water quality delivered to the UDM dental clinic and University hospital Clinic (UHC) for soluble iron byproducts and TDS levels, testing the effectiveness of Sterisil Straw filtration system in keeping heterotrophic counts fewer than the CDC’s recommended 500 or fewer CFU/mL for a year in dental unit waterlines, and assessing the mercury level present in water after rinsing instruments used in amalgam tooth fillings. Results showed that even with the presence of Sterisil Straw filters, bacterial growth occurred before 1 year. The number of CFU/mL varies depending on the frequency of use of the DCUs. This can be of concern for dental patients and health care workers alike. Changing the Sterisil Straw filters more frequently is recommended in this case.