Water quality: see https://www.sfpuc.org/sites/default/files/documents/SF_Regional_WaterQualityReport_CY2022.pdf https://www.sfpuc.org/sites/default/files/docum

Water quality: see https://www.sfpuc.org/sites/default/files/documents/SF_Regional_WaterQualityReport_CY2022.pdf https://www.sfpuc.org/sites/default/files/documents/SF_Regio... Efficiency: see https://www.epa.gov/watersense/point-use-reverse-osmosis-systems https://www.epa.gov/watersense/point-use-reverse-osmosis-sys... For example, a typical point-of-use RO system will generate five gallons or more of reject water for every gallon of permeate produced. Some inefficient units will generate up to 10 gallons of reject water for every gallon of permeate produced. In recent years, membrane technology has improved and some point-of-use RO systems have been designed to operate more efficiently, with some manufacturers advertising a 1:1 ratio of permeate to concentrate production, meaning only one gallon of reject water is generated for each gallon of treated water.