Before modern city living and city water supplies, we got much of the minerals, those things people spend so much on in the way of supplements, from ground water (or rivers, small lakes). You didn't need to drink milk \ take calcium when your water source provided enough calcium (and others minerals).
There are any number of under-counter water filtration systems, some that use multiple stages, some that are single stage (but use multi-stage filters). Many of the filters are interchangeable (not all of course). Most will filter out the majority of heavy metals, organic contaminants, chlorine, flourine, etc. Most will filter out bacteria and other "large" organisms. Some will help to remove calcium, however, as minerals are usually fully dissolved, they will simply pass through the filter. That is actually a good thing.