David W.E. Roberts wrote:

We were quite taken with the idea until we discovered that it is filled then
chemicals are added to stop the water going manky - so you are tubbing in a
chemical stew (much like a swimming pool).

Nah, 'chemicals' aren't so bad. Really depends what you're putting in
and how much. Also, if you're really fussy, you could go for a filter/UV
arrangement, with no chemical treatment.


I realise that a hot tub hold several times the amount of water that a
normal bath holds

About 10x


and also that most times the location is not chosen for
suitability for drainage or filling directly from the hot&cold, but has
anyone seen or built a hot tub which is plumbed in more like a normal bath?

I think that would be an abomination. The idea of wasting 1.5 tonnes of
water, and a huge amount of energy for a one off use is terrible. In
addition, you'd need a *huge* heater to get the water up to temp in any
reasonable timescale.


--
Grunff