David P writes:
What about chemicals/metals/minerals getting into the water from
parts of the hot water system?

It probably depends a lot of the water's pH and natural mineral and
gas content, but around here it is recommended that when preparing
beverages we use water from the cold tap. My understanding is that
copper dissolves better in hot water, so water that has been standing
in the hot water tank emerges with a higher copper content than water
that has been standing for equal time in cold copper pipes.

To avoid unwanted copper intake, fill your electric jug from the cold
water tap even though it will take a minute more to bring to the boil.
--
John Savage (my news address is not valid for email)