Instead of all the tanks and other longwinded systems, I have my pipes going
straight outside to the areas I want them. The bathtub drains to the roses,
via an old bit of 2" poly pipe, and a piece of motorbike tyre tube to give
me a flex joint at the house end where it comes out the bathroom wall. The
kitchen, bathroom sink and laundry drain straight out similar old bits of
pipe to a series of other areas of the garden. No complicated smelly tanks,
except to hold fresh water that I pump up from my well.

Mind you, on 160 acres, I have the grey water drains away from the house,
and the fresh water overflow when I fill the tanks going to the area close
to the house.

Hope this helps,
Peter