I just installed a whole house water filtration system with Carbon and conditioning tanks, plus UV. My wife made me have our water professionally tested (we used Xperiential). The test proved very good but three problem areas: Arsenic, PH, and Alkalinity. Arsenic was below EPA but the scientific community suggest mitigation despite that. So I did some research and found RO (Reverse Osmosis) could be used to mitigate Arsenic levels as well as other contaminates. In looking for under sink solutions, I came across the Waterdrop tankless system which featured 5 stage filtration, and a small under sink footprint. Since I had whole house filtration, I chose the G2 as opposed to the 7 stage PH600. Installation was simple, with the exception that I had to install an under sink electrical outlet that I was able to do myself. After installation and test for leaks, I purged the system for 30 minutes as instructed and did a quick check on TDS level. To my satisfaction, TDS was 5 which was better (at 20) than the bottled water we had been buying. My Tap water TDS averages 60. You can expect to have variations in TDS readings unless you run water through the G2 for at least 30 secs. Without doing this my TDS reading is at most, 20 and scales down to around 7 after expelling 8-16 ozs. Since I have whole house filtration before RO filtration, I'm not going to worry about that, especially since my highest TDS is still better than the bottled water brand we had been buying and importantly, mitigation of arsenic levels . The only thing I don't like about the system is the flow rate but for me, a fair trade off considering not having to lug and store cases of bottled water! I am a happy camper and very pleased with the quality of this system and the Waterdrop support.