Past exam of the medicine course of the University of Oxford / 1867 / Second examination / Forensic medicine and hygiene / 7 / Solution

A workable scheme has to deal with both transport and final disposal. At the house, collect excreta in suitably flushed closets; use sound, impermeable drains with sufficient fall and provision for inspection and cleaning. Traps interrupt communication between house air and sewer air, while appropriate sewer ventilation prevents the system from discharging its atmosphere into dwellings. Keep the drinking supply physically protected from drains and leakage. A sewer that carries filth away from a courtyard but releases it beside a downstream drinking intake has merely moved the danger.

Convey sewage promptly to a controlled outfall or disposal site, with pumping where the terrain requires it. One contemporary proposal was application to land by sewage irrigation, using land and drainage arranged to receive the flow rather than allowing stagnant pools. A period report on sewage irrigation at the Cumberland Asylum appeared in January 1866, establishing that this was an available contemporary option, not a later technology projected into the examination.^[ref]

The word “best” needs conditions. Water-carriage sewerage requires a dependable supply, engineering maintenance and an acceptable destination for the effluent. Where these cannot be provided, watertight removable receptacles with organized frequent collection can be preferable to an unreliable water system. Dry-earth sanitation was another period alternative, useful where systematic collection and suitable dry material could be assured. Neither an overflowing cesspool nor occasional removal after a nuisance has developed is a satisfactory urban service. Contemporary proposals competed over these very questions; there was no demonstrated single apparatus suitable for every town.^[ref]

Other waste organic matter requires a parallel service: covered receptacles, frequent collection of kitchen refuse and animal waste, cleaning of markets and slaughtering places, and controlled treatment or disposal away from dwellings and drinking supplies. Bulky refuse should not be pushed into house drains and allowed to obstruct them. The practical objective is continuous removal from contact with people, rather than accumulation followed by attempts to suppress the smell.

The present public health qualification is crucial: sanitation includes safe containment, emptying or conveyance, treatment and final disposal or controlled reuse. Neither chemical deodorization nor the apparently clear appearance of an effluent establishes removal of pathogens. Land application of untreated sewage must therefore not be presented as automatically safe for workers, crops or downstream users. Modern evaluation follows the whole service chain and its exposure routes.^[ref]