In article ,
"Sparks" writes:
I have installed a complete irrigation system in my garden, but would like
to use grey water if possible. (Water would be from the bath, shower and
hand basin)

Am I allowed to use it in my own garden?

Yes, unless you become subject to a drought order (in which
case the fact that you have used it once already still doesn't
give you the right to use it to water the garden).

If so, do I need to do anything to the water to make it suitable for use?

I don't think so. Make sure you don't wash anything more than
regular soap/shampoo/washing up liquid into it though.

I was thinking of installing a small tank with another pump (with a float
switch) that would also feed into the 1400L containers, but was unsure if
the water needed some kind of treatment to remove soap etc.?

No, but I would avoid storing gray water -- use it ASAP.
Tanks which get lined with soap and fat scum are going
to start smelling.

There may be some plants which don't like it (soap tends to
be alkali). I have used it on my lawn without any problems
in the past. I might hesitate to use it on plants grown for
eating.

--
Andrew Gabriel