Hydrosep®8 fl.oz. bottle. One 8 fl. oz. bottle can treat 5 to 20 gallons of clean potable water. Hydrosep's duration of effectiveness is dependent on what type of device it is used in: In a sealed pressurized portable or a air driven TWS shower system, Hydrosep has been proven effective for 180 days. In an unsealed gravity fed eyewash, Encon recommends cleaning and replacing the fluid every 90 to 120 days.