Heritage Open Day: David Sellers spent nearly 30 years as a Chartered Civil Engineer designing sewer systems for Leeds. His illustrated talk brings to light some milestones from the cholera epidemic of the 1830s to the environmental controversies of the present day. The sewerage network beneath our feet is taken for granted as one of the prerequisites of civilised life; it is very much 'out of sight, out of mind'. Consequently the history of our sewerage inheritance is hidden even more effectively than the sewers themselves.