The challenge test was performed to respond to the FDA clearance process. Samples were taken at the exit port of the Waterclave System to demonstrate Waterclave's ability of bacterial inactivation under extreme injection of countable bacterial numbers at the exit of the Waterclave System. The bacterial strain used was Pseudomonas putida introduced at numbers of 10 to the tenth with a flow rate that would assimilate 35 dental units functioning at the same time. After 10 days of incubation on R2A agar 0 bacteria was recovered.