Aqua Filter reverse osmosis membrane 50 GPD 8 l/h The Aqua Filter reverse osmosis membrane removes from the water the contaminants that may be present in the water, such as lead, arsenic, barium, chromium, mercury, sodium, cadmium, fluoride , nitrite, nitrate and selenium. TFC replacement membranes have been tested and certified according to the requirements of the International Organization NSF and Water Quality Association for their suitability in domestic drinking water filtration systems. They are certified to NSF/ANSI Standard 58.