The Unpumped Series ranges from 50gpd (8lph) up to 600gpd (95lph) and have the ability to perform efficiently at UK mains pressure, so long that this is above 43 psi (3 bar), as any pressure below this will not be suitable for the RO membrane to function. Our RO-50M (8lph) and RO-100M (16lph) models include a polishing DI resin stage on the bottom set of housings, whereas all other systems in this series do not include any resin and the bottom housings are solely for pre filtration..

https://vyair.com/product/ro1up-5-stage-unpumped-reverse-osmosis-drinking-water-system-50gpd-8lph/