:shock: Boiler man your correct mate, i have researched the system and it is how you say.
Loft tank and underground tank all fed by the 32 and 40 mm waste.
Re think needed and thanks for yr help, much appreciated
Is there any way to reduce bathroom waste pipes 32 and 40mm to 22 or 15 mm as i want to build a grey water system to water my garden and flush the bog
Cheers in advance for any tips