**1. Introduction: importance of non-networked sanitation to environmental and public health management**

An extensive body of research underscores the importance of safe sanitation in reducing the incidence of waterborne diseases, maternal mortality rates, infant mortality rates, malnutrition, as well as, engendering individual well-being, productivity, and dignity. A lack of contextually designed and well-maintained sanitation systems at the level of the individual, settlements, and region, contribute to pollution of groundwater, waterways, soil, and lead to adverse public health outcomes [1, 2]. Yet, up until the last decade, the Global South has had to contend with a complete absence of basic sanitation facilities among large segments of the population leading to the practice of open defecation. At the turn of the millennium,

2.36 billion people globally practised open defecation or had access to an unimproved toilet facility, with a stark disparity in levels of sanitation between low and high income countries. As per the WHO-UNICEF Joint Monitoring Programme (JMP), seven out of every ten individuals in low-income countries lacked even basic sanitation in 2000. More broadly, 70% of the global population without access to basic sanitation resided in low- and lower-middle income countries.

The push to increase 'improved sanitation' at the level of the household under the Millennium Development Goals (MDGs) has since transformed to the Sustainable Development Goals' (SDG) focus on 'ensuring availability and sustainable management of water and sanitation for all'. While the former targeted the elimination of open defecation and the use of primitive facilities like bucket latrines, hanging toilets, pit latrines without slabs, latrines flowing into drains or the open environment, the latter reinstated the goal with the additional aims of increasing levels of wastewater management and reducing water pollution.

The increased attention to wastewater management in the wake of the SDG era has led to an improved understanding of the different approaches urban and rural households across the world adopt to manage faecal waste. In the preceding decades, vast sewerage networks conveying wastewater from the source to a centralised Sewage Treatment Plant (STP) had dominated the imagination of the city, state, and national governments alike. The last few years have witnessed an enduring recognition of how the sewerage system is unsuited to provide citywide sanitation as a universal gold standard [3]. Though the high population densities of bigger cities and metropolitans justify the cost of the networked solution to sanitation, given how fast many of the cities in the Global South have been growing, service delivery systems tend to fail in keeping pace and are left to play catch-up. Secondly, the low population densities of smaller cities, peri-urban areas, and rural settlements often do not justify the creation of sewerage systems, which are not only resource-intensive to construct, but also to operate and maintain.

By default, in the continuing absence of the networked sewerage system, improved and safe sanitation beyond the toilet takes the form of 'non-networked sanitation'. In its simplest definition, as per the International Organisation for Standardisation (ISO), non-networked sanitation comprises any sanitation system treating human excreta that operates without connection to any sewer or drainage network. According to the WHO-UNICEF JMP, in 2017, the number of people depending on non-networked sanitation is just as many as those served by sewerage systems at an approximate 3.1 billion. Unpacking the reliance on the two different types of systems across developmental regions shows that while the reliance on non-networked sanitation (in the form of septic tank, improved pit and other such systems) is much higher in low- and lower middle- income countries, it is not insignificant in upper middle- and high- income countries (**Figure 1**).

Non-networked systems take the form of septic tank systems, single pits, twin pits, composting toilets, container-based toilets, and newer varieties that convert faecal waste into fully treated liquid and solid end-products on site. Interestingly, both the conventional form of the septic tank system and the sewerage system emerged during the same period – the late 19th century - as alternatives to privies, cesspools and cesspits, that had led to disease outbreaks in rapidly-densifying European cities. The septic tank system, comprised of a watertight septic tank and a porous soak pit in series, was patented by John Mouras as the 'Mouras Automatic Scavenger' in France in 1881. The septic tank system soon landed on American shores, from where it spread widely as a low-cost technology for newly urbanising and low-density areas. Within decades, the failing systems spurred improvements in design and standardisation throughout the twentieth century. Guidance on best practices in the design of a septic tank system, known at the time as 'Typical Farm

*Managing Non-Sewered Sanitation for Achieving Sustainable Development Goal 6 in India DOI: http://dx.doi.org/10.5772/intechopen.98597*

#### **Figure 1.**

*Dependence on different types of sanitation systems.*

Sewage Disposal System' was available in the 1920s in the USA. Formal standards also begin to emerge during this period, with the British Code of Practice first coming out in 1956 [4].

With the proliferation of the sewerage system across Europe, it began to grow in popularity as the standard model for sanitation in cities of the Global South as a result of colonial influence. As a counterpoint, the attempts to mainstream sewerage alternatives started in the 1970s with a World Bank research project that established that non-networked sanitation, or on-site sanitation, could offer a service to public health equivalent to the sewerage systems and at a lower cost. John Kalbermatten, leading the World Bank research, emphasised the importance of adopting a multitechnology strategy (sewered and non-sewered/on-site) in Urban Sanitation Planning to ensure universal coverage of adequate sanitation services [5].

Furthering this emerging unified discourse on sanitation, the United Nations declared the 1980s to be the 'International Water Supply and Sanitation Decade'. The declaration led to the formation of a Technical Advisory Group (TAG), comprised of the United Nations Development Programme (UNDP), World Bank, UNICEF, and members from the Government of India, in 1983, which recommended the 'twin-pit pour-flush latrine' as an appropriate low-cost sanitation solution for both rural and urban areas. Accordingly, the first Indian programme focused on sanitation, the Centrally Sponsored Rural Sanitation Programme (CSRSP), adopted the twin-pit system, a preference that continues in the latest national programme, the Swachh Bharat Mission (the Clean India Mission) [6].

The Group's 'Report of the Committee on Design Criteria for Pour-Flush Waterseal Latrines in Rural Communities of India' directly assisted the Bureau of Indian Standards (the national standard-setting body) in issuing the 'Code of Practice for Sanitation with Leaching Pits for Rural Communities' in 1988. The Code discusses various technical aspects of construction and maintenance of leaching pits and allows for both twin pits and the 'single pit', provided the latter is 'desludged by a vacuum tanker since its contents contain pathogen'. The Indian Code of Practice for Installation of Septic Tanks similarly discusses the design and construction criteria for septic tanks and subsoil dispersion systems in two separate parts first issued in 1963 and 1964 respectively, and significantly and substantively revised in 1985.

In the present time in India, as in other developing countries of the Global South, households construct the sanitation system, whether septic tanks or leaching pits, in situ. In contrast, developed countries that had targeted the issue of basic

sanitation much earlier have created more mature ecosystems for non-networked sanitation. From the in situ construction of the systems driven by households, they have advanced to greater dependence on industrially manufactured and standardised on-site systems in a variety of materials like polyethylene and fibrereinforced plastics, eschewing the traditional brick-and-mortar. Secondly, research and industrial innovation have led to newer on-site 'packaged' systems that perform the function of primary, secondary, and tertiary treatment in one compact unit. Thirdly, more than the unit itself, the regulatory and operative models governing non-networked sanitation and these systems have similarly evolved.

With the flagship governmental programme, Swachh Bharat Mission (SBM), segueing into its new phase, the national focus has shifted to challenges of managing faecal waste beyond the toilet. Both the urban and rural versions of SBM Phase II, announced in 2021 and 2020, respectively, mainstream Faecal Sludge Management (FSM), or the safe management of faecal sludge and septage evacuated from on-site systems as they fill up over time at an off-site facility, or a Faecal Sludge Treatment Plant (FSTP). While FSM solves the gaps in achieving safe and sustainable sanitation beyond the individual premises and is critical, a sole focus on FSM often excludes the discussion on the quality of on-site systems and its improvement from the agenda. With investments in sanitation continuing to intensify as we enter the last decade of the SDG era, it is important to evaluate the need for systematic improvement in the on-site infrastructure for ensuring that the entire service chain of sanitation is secure. The issue is only underscored by a growing institutional acceptance of the on-ground common knowledge that on-site systems do not comply with basic safety standards [6, 7].

The present paper reviews the findings of a novel sample survey focused on onsite systems administered to 3,000 households across urban India. It offers insights on the typology and compliance status of these systems and how learning from advanced contexts, the whole ecosystem for non-networked sanitation can evolve in India and similar contexts across the Global South.
