Water filtration systems can remove impurities and contaminants found in tap water, including lead, chlorine, and bacteria. Some remove more than others. But in many cities is just not necessary to even filter tap water for human consumption.
I'll never forget visiting Switzerland years ago with a tour group, and just after we were told Switzerland has the purest drinking tap water in the world, there goes a bunch of our group into a supermarket to buy bottled water.
If you're all about eliminating single-use plastic from your life, but your tap water is straight up undrinkable, this task gets a bit difficult.
See https://mashable.com/roundup/best-water-filters/ which gives a few options, some of which will even filter well water