4 Stage Reverse Osmosis System The 4-Stage drinking water system includes: Sediment/Carbon Pre-filter (S7028)m TFC 50 gpd membrane (S1229RS) (35 gpd +/- 7 gpd actual production based on TDS level), Activated Carbon Post-filter (S7025), GAC inline filter (S7206W-JG),3.1 gallon storage tank volume (1.8 gallon capacity), Long reach air-gap faucet, Automatic shutoff, Installation parts kit with instructions, 28-42 gallons per day of 'Bottled Water' quality water based on TDS level!, Unit dimensions are 15" H x 12" W x 4" D, Storage Tank dimensions are approx. 9.5" D x 17" H (with valve on top of tank), Max limit of 10 Grains Per Gallon Water Hardness, Less than 0.1 ppm Iron, pH 3 - 11, Max TDS - 2000 Owner's manual