The fridge at the new domicile has an RO filter.
It makes a huge difference. I changed the filter out not long after moving in. An alert came up.
The old filter weighed a pound or so. New filter and box, feather light.
I have a cheap water quality tester (my daughter gave me) that I use before replacing filters. The strait tap water reads a 98 (quantity of contaminants). The water out of the filter, around 1 or less.