Water Filtration
Even if you live in a country with high quality drinking water you may want to do so if you live in an older house (which may have lead pipes) or if you'd like to avoid other contaminates still likely to be in your water such as hormones (from contraceptives), psychotropic medications (such as anti-depressants) and PFAS - you'll need a dual/two stage filter with or without reverse osmosis to deal with PFAS.1
They sometimes strip away beneficial minerals too. These include magnesium and calcium, as well as iron and manganese, which are eliminated to make water softer and prevent discolouration, respectively. Filters can also remove fluoride, which some municipalities add to tap water to help combat tooth decay. We shouldn't be relying on our drinking water as our main source of minerals. Sponge-like activated carbon filters, in particular, can serve as breeding grounds for nasty bacteria.