I open the doors and air out the house frequently, and I drink tap water. My mother lived to just short of 98 years old doing the same, so I expect I will be just fine.
It is to the financial advantage of various businesses to create fear of drinking water (for example), so that one would buy their water filtration systems. Show me relevant, independently collected life expectancy statistics and maybe I'll think about it. The human body is pretty tough and can put up with a lot.
"You can never cross the ocean until you have the courage to lose sight of the shore." - - - C. Columbus