Where sewers cannot be laid and pit latrines will not work, one option is to catch waste in sealed containers and haul it away to a treatment site. Tilmans and colleagues report on a pilot of that arrangement, delivered to households in Cap Haitien.

Their measurements cover a densely built informal settlement: how much excreta the population produces in a week, what share of it is safely carried off by household and shared container toilets, and what the operation costs. Unmanaged faeces dropped by roughly three and a half times, and among households on the service, open defecation and bagged waste thrown into the street all but disappeared.

Costs ran above those of conventional piped sewerage at scale, though the authors expect that gap to narrow as such services grow. They end by weighing what it would take for planners and policymakers to treat container systems as one of the standard choices available to fast-growing cities.