Hey guys thanks for all the advice, brill.
Just to clarify, our house is above our garage and although we have mains water in garage there is no drainage anywhere near, as for gutter down pipe we dont have on as we are in a terrace of 4. All built above our garages, have checked no one has driveway drains.
All our household drainage is in the back gardens so would mean pumping waste water up stairs and thru the house so out of question. our houses built on a steep slope.
Like the idea of the 6mm pipe out for waste. Please tell me as I've never seen a system working, is the waste a high pressure and constant flow or more like a slow trickle? Would be interested to know if any one can help.....
Ps, TDS meter arrived today, and on average over 3 readings i was getting 96ppm, with a temp of around 12c. hope all this info helps and once again guys thank you so much for all your help.
Goochie.