Over 1.5 billion people still do not have basic sanitation services, such as private toilets or latrines.
Of these, 419 million still defecate in the open, for example in street gutters, behind bushes or into open bodies of water.
In 2020, 44% of the household wastewater generated globally was discharged without safe treatment (1).

Improvements in urban sanitation in the 19th and 20th centuries in Europe and North America resulted in significant inhibition of the spread of infectious disease. Subsequently, centralized waterborne sanitation was ranked as one of the top medical and engineering achievements of the 20th century. (1,2) However, urban development and sewers have not always progressed hand in hand. In Harappa (modern day Pakistan), underground sewers for conveying human excreta were built as early as 3000 BC, with every house having a flush toilet. (3) Since then, sanitation services have fluctuated with changes in civilizations, from the Cloaca Maxima in ancient Rome to no central sewer in London until the end of the 19th century. (2) Diverse improvements have been made with flush toilets, piped sewers, and wastewater treatment, but this impetus has not been sufficient to solve the sanitation challenge on a worldwide basis. Currently, only 64% of urban residents globally are served by sewers, (4) and it is not known how much wastewater actually receives effective treatment. (5) The flush toilet is considered the gold standard as it conveniently removes feces and urine from sight and smell, but without adequate capture and conveyance, community-scale health and environmental benefits are obviously not achieved. This sanitation challenge in urban areas is increasing with rapidly growing cities (e.g., increase of 1.3 billion people between 2000 and 2017), (6) along with climate change, water scarcity, and migration. Sustainable Development Goal (SDG) targets and sanitation as a human right are severely impeded by cultural reluctance, profound misconceptions, and honest ignorance, and achieving them will require us to overcome barriers that are preventing the roll out of appropriate solutions.

Research and practice efforts are often focused on advancing solutions at treatment facilities, (7) but the protection of public health in urban areas relies as heavily on capture and conveyance to treatment, to avoid pathogen exposure at the source of production. The objective of this paper is to challenge common misconceptions around global paradigms for the management of sanitation, focusing on capture and conveyance to treatment. We postulate that these misconceptions lead to misinformed decisions that hamper progress in access to services in high-density urban areas and have profound detrimental downstream effects...

...Why Does Terminology Matter?

The World Health Organisation categorizes sewer-based and rural land-based solutions as “established”, (13) meaning that technologies are reliably understood to the level where globally accepted guidelines exist on how to design, build, and operate them. Research into activated sludge has been taking place for more than 100 years, (7) and guidelines for land-based treatment with septic tanks (14) and pit latrines (15) have been in place for more than 70 years.

By contrast, solutions for full and safe management of sanitation in urban areas that rely on at source storage and road-based transport remain mostly as “emerging” or “transferring” solutions. (13) This mode of service provision is widespread and rapidly gaining acknowledgment as a viable solution, although solutions have not yet been established. This is increasingly called “fecal sludge management” or “FSM” in the development sector, but the term is poorly defined...

...1. Septic Tanks and Pit Latrines in Urban Areas Are in Fact Not Septic Tanks and Pit Latrines...

...2. Existing Categories Are Not Analogous to “Safely Managed Sanitation”...

....4. Wastewater Streams from Human Feces Are Not All the Same, and This Has Significant Impacts on Treatment...