Water purification...?

There certainly are residual chemicals in the so called "clean" water supply. Some occur naturally, such as calcium salts, sodium chloride, etc. Some are added purposefully such as chlorine and calcium fluoride. The most problematic are those originating in our household effluent water, such as phosphates and detergents. Industry adds its load as well and certain products which are known to be potentially very harmful such as APEO based surfactants that can form synthetic hormones such as the oestrogen you mention are banned in many countries.