Just wrapped up tankless RO installation under kitchen sink! Space was TIGHT but made it work. System provides 400 GPD - plenty for family's needs. Installed dedicated faucet on sink deck and connected drain line properly with air gap. Water efficiency is 1:1 ratio (huge improvement over old 4:1 system). Pressure tested all connections - zero leaks. Ran system through 3 flush cycles before final water test. TDS down from 320ppm to just 15ppm! Incredible water quality now. Customer very happy with improved taste.