Under the sink, not the whole house
An under-sink filter or a reverse osmosis unit serves the kitchen tap. It does not treat showers or the water heater. Installation searches overlap with reverse osmosis; if the goal is dissolved solids or a certified reduction, start on the reverse osmosis page.
Carbon under the sink is a taste and odor option on a public supply. It is the wrong single answer for a well with iron or bacteria.
Questions people ask
Under-sink filter or reverse osmosis?
Carbon is for taste and chlorine. Reverse osmosis is for a broader drinking-water reduction, with a certified claim for what it removes. The kitchen tap is the right location for either.