if anyone's looking for a reverse osmosis water filter system that doesn't require you to upgrade your whole house, i have this under-sink unit and it is *great* and it's $300 off on amazon right now. best price i've seen it.
install was surprisingly not too bad, hardest part was just drilling a hole in the counter for the spout.
https://www.amazon.com/Waterdrop-Reverse-Osmosis-Filtration-Tankless/dp/B0987FCQQW