In message , Chris Hogg
writes
On Thu, 23 Jun 2011 20:41:44 +0000, lannerman
wrote:


I have a friend with an indoor swimming pool who uses a lightly
chlorinated system. Every so often he has to back wash the filter and he
uses this back wash water to irrigate a very mature woodland garden!
Does anyone know wether or not this slightly chlorinated water would
harm existing very mature Rhododendrons and Camellia's ?? I would be
very grateful for your comments.
thanks, Lannerman.

AIUI chlorine from chlorinated tap water evaporates fairly quickly if
the water is left to stand for a while (a day or two, maybe, I'm not
sure). Whether this is true for swimming pool wash I don't know, but
if you can smell the chlorine, it's evaporating. When it's stood for
long enough so that you can't smell chlorine, what's left probably
won't do much harm as the organic matter in the soil will take care of
it. After all, nobody thinks twice about putting chlorinated tap water
on their plants. But I would be worried about other salts that might
be there. For example, 'Milton' contains ordinary salt as well as
chlorine (as hypochlorite), and if salt is present, I wouldn't put it
on the garden.

Chlorine is odourless. What you can smell are the amino-chlorides which
are formed as the chlorine does it's job.
--
hugh