In article ,
says...
"Dave Liquorice" wrote:

On Tue, 4 Dec 2007 13:48:46 -0800 (PST), wrote:

do you include the grey water to keep the working volumes up, or do you
restrict it to blackwater and rainwater?

Rainwater is a no, no. The volumes of even a small shower on a decent
sized roof will flush a septic tank through far to quickly...

What is the ill effect of that?

I am no expert but the bacteria has to have some time to digest the
sewerage componant before the discharging water will be safe to soak away
into the surrounding land. It is not normally to put rain water through a
septic tank, this normally goes to seperate soak aways, often several one
for each down pipe.
--
Charlie Pridham, Gardening in Cornwall
www.roselandhouse.co.uk
Holders of national collections of Clematis viticella cultivars and
Lapageria rosea