Quotation from: General Science

Written by: Bertha M. Clark

It is not necessary that water should be absolutely free from all
foreign substances in order to be safe for daily use in drinking; a
limited amount of mineral matter is not injurious and may sometimes be
really beneficial. It is the presence of animal and vegetable matter
that causes real danger, and it is known that typhoid fever is due
largely to such impurities present in the drinking water.