**3. Improving on-site systems to achieve Sustainable Development Goal 6**

Due to their unchecked and unregulated proliferation, on-site systems have mutated on the ground in response to the needs of the households (**Figure 4**). In urban India, households maximise the size of their on-site system subject to constraints of capital and space to reduce the incidence of maintenance or desludging events. The behaviour evinces the household's conception of on-site systems not as an active decentralised wastewater management system, but instead as a passive faecal waste containment structure (possibly rooted in the desire to 'flush and forget', if they can afford to, like sewered households). Overall, the phenomenon is not endemic to India, and similar issues in the quality and common perception of on-site systems prevail in countries like Bangladesh, Indonesia, Vietnam, and others in the Global South [16].

#### **Figure 4.**

*Characteristics of on-site systems in urban India (reproduced from: Dasgupta S, Agarwal N, Mukherjee A. Unearthed - facts of on-site sanitation in urban India. Centre for Policy Research: New Delhi. https://doi. org/10.13140/RG.2.2.11717.06887).*

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

As non-networked sanitation begins to find a place in mainstream planning and governance systems for citywide sanitation, it would be critical for city, state, and local governments to correct for the deficiencies in the household-level on-site systems for maximising the gains from sanitation investments. A three-point agenda, as discussed below, can guide the way for improving the entire ecosystem surrounding on-site systems towards achieving Sustainable Development Goal 6.

### **3.1 Shifting paradigm to on-site treatment without depending on soak pits and dispersion trenches**

A septic tank, as a standalone unit, is not enough to manage wastewater on-site. A subsoil dispersion system together with the tank constitutes the conventional 'septic tank system' as a complete solution. Without a soak pit or dispersion trench, which release the tank effluent into the subsurface for further nature-based remediation, the effluent must either be treated more completely at the household level before being discharged into the environment or conveyed to an off-site treatment facility through closed channels for treatment. The applicability of each strategy changes based on context. For instance, soak pits and dispersion trenches are a low-cost and low-maintenance solution for effluent management in rural and low-density peri-urban areas. In areas with high density, conveyance and off-site treatment of tank effluent could work if retrofitting and interception of existing drainage channels is possible, or if the costs of creating such a system (like a small bore sewer system) anew are still lower than that of developing a full-sized sewerage system. Alternatively, higher in-situ treatment of the wastewater could help achieve a high level of sanitation without requiring significant investments in city-level infrastructure.

Each of the three strategies demands significant systemic changes to the broader ecosystem within which to implement them. For instance, both the construction of soak pits alongside existing septic tanks and the upgradation of septic tanks to newer, more advanced on-site systems require the willing participation of the household. The feasibility of the latter is additionally contingent on the availability of a flourishing prefabrication industry for on-site systems. Similarly, conveyance and treatment systems require sustained funding to build and operate.

Despite their conventionality, subsoil dispersion systems are unsuited to urban areas. Hydrogeological conditions form only one set of factors influencing the suitability of subsoil dispersion systems. Their spatial density also acts as a critical and limiting factor - with the recommended threshold of spatial density varying in the literature from as low as 16 to 495 units per square kilometres. In India, most cities lie at the higher end of the range and are denser still at the neighbourhood level, rendering the promotion of subsoil dispersion systems an unsuitable option [9]. Therefore, it is imperative that governments move on from viewing subsoil dispersion systems as a simple and appropriate fix to other strategies (**Figure 5**).

#### *3.1.1 Learning from Japan*

Up until the Second World War, Japan was primarily an agrarian society and relied on pit toilets, the faecal waste and sludge from which would be evacuated and used as a soil conditioner in farming. The government pursued the development of sewerage systems in the 1970s as the country started urbanising and densifying. With a rising level of affluence, even households in unsewered areas began transitioning to pourflush toilets and created a need for a system that could serve as a complete on-site treatment system in the absence of a sewer connection.

**Figure 5.**

*Density of septic tanks at the city-level in India (reproduced from: Dasgupta S, Agarwal N, Mukherjee A. Moving up the on-site sanitation ladder in urban India through better systems and standards. J. Environ. Manage. 111656. https://doi.org/https://doi.org/10.1016/j.jenvman.2020.111656).*

The Tandoku-shori Johkasou (translated as blackwater-only on-site treatment system) gained popularity among households during this period and witnessed proliferation alongside the sewerage system, albeit without governmental regulation. However, within a couple of decades, the persisting issues of water pollution, ascribed to dysfunctional Johkasou systems, emerged at the forefront. To plug the gaps in sanitation and environmental management, the government enacted the Johkasou Law, or the Packaged Aerated Wastewater Treatment Plant (PAWTP) Law, in 1983. The Law enabled the standardisation of the Johkasou for complete treatment of blackwater, its manufacturing, installation and maintenance. The national and local governments created a subsidy programme to enable the rapid diffusion of the improved Johkasou among non-sewered households. In 2000, recognising that treating only blackwater was not enough for environmental protection, the government further amended the PAWTP Law to phase out Tandoku-shori Johkasou in favour of the Gappei-shori Johkasou that treats both black and greywater in the same system [16, 17]. As per the latest data from JMP (2017), Johkasou and older on-site systems continue to serve 23% of the country's total population.

### **3.2 Encouraging adoption of prefabricated on-site systems to improve performance and standardisation**

The speed of diffusion of improved on-site systems and technology, in general, is dependent on a mix of social, economic, and technical factors. Existing research has described the adoption of innovation as 'primarily the outcome of a learning or communications process' [18]. In a densely-populated and urbanising country like India with low levels of baseline technical expertise on safe on-site systems among masons and weak local governance capacities for their regulation, achieving diffusion of new systems at speed and scale would follow a tedious and long trajectory with in-situ construction.

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

A small set of, and often regional, prefabrication industries for on-site systems already exists in the country. The national and state governments should collaborate with the industrial players to create a portfolio of prefabricated on-site systems that perform advanced (secondary/tertiary) treatment of incoming blackwater and greywater. As part of such a strategy, the government should consider subsidising either the industry or the households directly to bring down the cost of prefabricated on-site systems, the latter like in the case of Japan, and make them competitive with the dominant practice of in-situ construction. Alternatively, or in complementing the subsidisation, the government could adopt a command-andcontrol approach where it mandates the adoption of certified prefabricated on-site systems among certain categories of users, such as commercial centres, institutional buildings, apartments, and others.

### *3.2.1 Learning from Malaysia*

Malaysia has been one of the flag-bearers of non-networked sanitation and FSM among developing countries, with 20% of its population dependent on on-site sanitation as per JMP (2017). The country has experimented with different frameworks to streamline the co-existence of non-networked sanitation and sewerage systems, as well as, created specific models for the governance of the former, including scheduled desludging. Until the 1990s, septic tanks constructed in-situ were the predominant on-site systems in the country. As a small prefabricated industry for on-site systems began to flourish from then onwards, the Malaysian regulators took cognisance of the opportunity to effect a fundamental shift in the sanitation sector and issued the Malaysian Standard 2441–1 and 2441–2 for the quality-control of the prefabricated systems.

In its first part, the standard notified the design of an improved or enhanced septic tank combining a settling unit with an anaerobic filter for up to 30 population equivalent (PE). The second part covers those systems that perform higher treatment still through aeration and are appropriate for applications with 31 to 149 PE. The distinction between the two types – aeration-based for higher treatment and non-aeration-based for moderate treatment – realistically accounts for the need for incremental improvement. Within a couple of decades, in-situ construction of onsite systems is on its way out, with the prefabricated system being cost-competitive and more convenient for households.

### **3.3 Creating robust city-level planning and regulatory ecosystems for on-site systems**

Rapid urbanisation and laggard service delivery systems have created new landscapes for the implementation of non-networked sanitation. Innovation in system design helps meets public health and environmental needs in these evolving contexts. However, the adoption of innovation and continuous process improvements are not possible without fundamental shifts in the encompassing ecosystem for planning and regulating urban infrastructure. Strong city-level planning systems are imperative to ensuring that households pick the correct option in onsite systems and construct or install it as per the prescribed guidelines. Secondly, a robust regulatory could help foster regular engagement with on-site systems and enable better performance through (a) monitoring of its overall compliance and quality and (b) identifying the need for desludging for improving operational performance. For example, in the case of urban India, the latter could look like local governments contracting desludging service providers to undertake scheduled inspections of on-site systems in addition to their primary responsibility.

#### *3.3.1 Learning from Ireland*

Ireland has one of the significant dependence on non-networked sanitation among countries of the Global North. As per JMP (2017), 32% of Ireland's total population depends on on-site systems – with the proportion being more than twice as high at 77% in rural areas. Since low-density rural areas are the major contributors to the dependence, the septic tank system continues to be a viable and the dominant type of system in use. Unlike India, where the Code of Practice recommends against treating 'wastes containing excessive detergents, grease, and disinfectants' in the septic tank, the Irish Environmental Protection Agency (EPA) clearly states that 'greywater in all circumstances be directed to the wastewater treatment system'.

The recently updated 2021 Code of Practice (CoP) for Domestic Waste Water Treatment Systems provides detailed guidance on on-site systems serving PE of 10 or less. The CoP behooves households to ensure that their on-site system complies with EN 12566, the standard for prefabricated assembled/packaged on-site systems, including septic tanks. The CoP requires households to select from the available onsite systems in consultation with the local authority following a site characterisation of their lot. It also discusses the appropriate desludging rates for septic tanks based on the different number of users and sizing. What is unique to Ireland is not its guidance and regulatory framework for on-site sanitation but its data-led inspection plan for monitoring and continuously improving the state of existing on-site systems.

Following the European Union Court of Justice ruling against Ireland under the 1975 EU Waste Framework Directive (Case C-188/08) in 2009, the country promulgated the Water Services (Amendment) Act 2012, which requires the EPA to prepare a national plan for inspection of at least 1,000 on-site systems annually [19]. The Act also requires households to maintain records of desludging. Since then, the EPA has carried out inspections in 2013 and 2015, with the third inspection plan for 2018–2021 underway. The latest inspection report from 2019 found that 51% of the inspected systems had failed, and 26% were a risk to human health or the environment. Under its new grant scheme, these failing systems are eligible for a grant worth €5,000 for improvements. The report noted that 73% of the systems that failed in previous inspections had been fixed.
