Nick Maclaren wrote:
I water mine with tapwater a lot of the time with no trouble, and
most people classify this water as hard. I don't, having lived in
South Wiltshire, but Cambridge water is definitely not soft.

Reminds me, completely off topic, of when I used to live in Cambridge (when
I was in last year of junior school) - I hated the tap water, couldn't drink
it at all, and it's probably where I learnt to dehydrate myself terribly
during the day! I remember the lunchtime tables with jugs of really nasty
tasting, slightly warm tap water, and nothing else. :-(
However, in the girls toilets was a water fountain and the water tasted
/totally/ different. Someone tried explaining to me that it was because
that water was pumped up straight from the chalk bedrock (chalkrock? :-) but
I have no idea how feasible this might or might not be. It struck me as
unlikely, but it was /really/ different tasting!