inhouse/inpipe filtration?

i read some place that it's possible to make a filtration system with
little modification to your houses plumping system so that there is no
need for tank replenishment and filtration components (Carbon and
cotton) costs would be greatly minized because you can place a common
drinking filter in the pipe. Is this true? Does anyone have any
information about something like this? Also does anyone have a link to
a file or a how to or some blue prints?