The Waterdrop D6 was an easy installation, single filter with pump (no holding tank). Water tastes fresh and clean. Utilized the second outlet behind my dishwasher for electrical power for the D6 internal pump. Total dissolved solids (TDS) numbers stay well under 100 most of the time under 50, seeing 20 is not uncommon. The cool part is its displayed right on the faucet. I like the pump feature as it puts out a steady stream of water with no worries of depleting a holding tank typical in the older style under sink RO systems. So far I love it! Pros: Clean stylish design Less tubing and water connections with quick connect feature Less chance for leaks! Chased them all the time with the older style system. Pump Driven, no holding tank that runs out of water TDS readout, you can monitor the quality of the water and filter health ONE FILTER changed at a 1 year interval (time will tell) No requirement to mount a filter rack in the cabinet, the single unit sits neatly inside Cons Had to go to the local hardware store to purchase a tube compression fitting adapter to connect to the under sink cold water with the "T" fitting provided in the kit. The "T" fitting had everything but the adapter.