Waterdrop Instant Hot Water Dispenser Reverse Osmosis System. 【𝟮:𝟭 𝗽𝘂𝗿𝗲 𝘁𝗼 𝗱𝗿𝗮𝗶𝗻】 The tankless RO water filtration system has a fast& stable water flow of 600 GPD and high hot water flow rate of 0.4 gal/min, and you can fill a cup of water within seconds.