"Dave Plowman (News)" writes:
In article ,
John Savage wrote:
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.

First I've heard of copper dissolving in hot water. How long does it take
for the pipes to disappear?

No one knows; we throw out the HWS as soon as one tiny spot in the copper
coils corrodes all the way through. Wasteful innit?

The time this takes varies a lot with what's in the water you feed the
system. 30 years for rural rainwater, 8 years for caustic acid rain. But
you'll notice that cold water pipes of similar gauge are set to last for
centuries.

Copper dissolves in cold water too, but more will dissolve in hot. If
you regularly drink tap water from a building tap that has not had water
running through the pipes for days, it's best to first run off some to
clear the copper piping of water that has been stagnating there for a
long time. Even the cold water pipes.
--
John Savage (my news address is not valid for email)