Can anyone help me? A friend of mine is looking to install a new toilet/shower room and intends to connect the drains to the existing pipes which run from his house to his septic tank. He's getting building regs for the new work but the fall on the existing drainage pipes isn't enough to comply with builing regs (it never had building regs in the first place and has been like that for over 10 years). The do have problems with blocked drains two or three times a year. Will the building inspector accept the new drainage being connected into the existing drainage even though the existing drains don't comply? Or will he insist on either a new run to the septic tank or the existing drain run being amended so that it complies?