The last stage of having pure, clean water is to filter it on the way out of the tank. There are all sorts of filtration options to cater for everyone’s desire.
From a basic sediment filter, to dual sediment/carbon filtration, triple/quadruple filtration with UV light to name a few. Different cartridges are available and can take out heavy metals, bacteria and organic compounds to make the water safe for drinking. UV light can kill 99.9% of bacteria in the water, which some people like to have that as peace of mind.
I tend to think I pick up more bacteria from shopping centres and medical centres than I do from my tank water, so I tend to go middle of the road with my filtration.