Bacterial numbers per ml in DUW can reach several millions overnight.
Opportunistic bacteria such as Legionella pneumophila and Pseudomonas aeruginosa have previously been revealed in DUW biofilms.
A symposium held at Trinity Collège, Dublin, Ireland, in Sept 2006 reached the consensus that output water quality should comply with ADA standard (Total Viable Count [TVC] <200 cfu/ml). This count should not include human pathogens (E.coli, Entecoccus spp, Pseudomonas aeruginosa, Legionella pneumophila).
- In Europe, it is recommended that only water of drinking water quality may be used in dental chair unit. In Europe, drinking water quality is TVC < 200 CFU/ml.
- In USA/Australia , drinking water quality is TVC < 500 CFU/ml
- In Japan , drinking water quality is TVC < 100 CFU/ml
- In France, water for any medical application should be TVC <500 CFU/ml and absence of Pseudomonas aeruginosa for sourcing water (entrance water) and TVC< 200 CFU/ml in wayout with absence of.