Safe faecal sludge emptying and transport: compliance challenges and models for a public good Open Access

Urban on-site sanitation is increasingly recognised as a public good, and ensuring access to safe services as a government responsibility (Joseph et al. 2024). The role being taken by many governments reflects a wider trend of regulatory capitalism, where regulation rather than the direct provision of public services is the expanding role of government (Levi-Faur 2005; Lerebours et al. 2021b). This shift occurs alongside the privatisation of services and expectations that market mechanisms would finance sanitation service coverage (Levi-Faur 2005; Rosenqvist et al. 2016).

The significant negative externalities of unsafe sanitation are difficult to quantify and attribute. Unsafely managed faecal sludge (FS) pollutes ecosystems and creates a disease burden that disproportionately affects low-income neighbourhoods (Peal et al. 2020; Wolf et al. 2022). Effective regulation is essential to address market failures and protect public goods across the 81 countries where most of the urban population relies on FS management (Baldwin et al. 2011; JMP 2022).

FS emptying and transport (E&T) is considered part of the sanitation chain, which could be more easily outsourced and regulated (Kone & Chowdhry 2014). FS E&T services in low-income urban areas are frequently delivered by a heterogenous private sector, ranging from sizable formal enterprises running vacuum tankers to individuals informally servicing their local community with shovels and buckets (Lerebours et al. 2021b; Dutton et al. 2022).

National regulatory frameworks for FS E&T are rapidly evolving. At least 65% of countries now have some form of regulations and mandated authorities in place, reflected in a growing body of literature (Lerebours et al. 2022; WHO 2023a). In many cases, a multi-level regulatory system is created, with mandated authorities regulated by a national body, explicitly or implicitly delegating service delivery to the private sector and acting as local regulators. Despite this rapid and positive evolution, legal or regulatory frameworks may still be partial and fragmented (WHO 2020). Drivers and barriers to compliance in the provision of safe FS E&T are not well documented or understood (Lerebours et al. 2021a).

Understanding the compliance responses of FS E&T service providers is critical to ensuring that these regulatory frameworks are translated into practice and achieve their intended outcomes to safeguard public and environmental health (Parker & Nielsen 2017; IWA 2022). The Organization for Economic Cooperation and Development (OECD) Regulatory Policy Outlook (2021) reflects compliance research, evidencing the complex responses of individuals and organisations to regulation, with deterrence and interest offering only a partial explanation (Kagan et al. 2011). If regulation does not take a bottom-up compliance perspective, then individual acts by service providers ‘…of foot dragging and evasion … may, in the end, make an utter shambles of the policies dreamed up by their would-be superiors' (Scott 1985).

In this study we aim to understand the challenges, in order to develop a framework to build compliance of FS E&T service providers. The research extends and adapts the holistic model of business compliance developed by Parker & Nielsen (2017) to be appropriate for FS E&T services.

An initial literature review was used to develop a series of statements on challenges and good practice. These were expanded and evaluated through a two-stage Delphi study (Beiderbeck et al. 2021). The Delphi study findings were then used to structure a review of the academic and practitioner literature on urban sanitation. Complete findings were assessed against the wider regulation and the compliance literature and used to adapt and extend the holistic model of business compliance.

This study looks at provision as defined by Ostrom et al. (1993), addressing the problem through consideration of policy and regulation. There are a wide range of possible definitions of regulation, ranging from a narrow view of a specific set of commands to incorporating all forms of social control or influence (Baldwin et al. 2011). Regulation is defined in this study as ‘a process involving the sustained and focused attempt to alter the behaviour of others … [to reach a] defined outcome’ (Black & Kingsford Smith 2002). The ‘outcome’ is achieving national policy goals for universal access to safe sanitation (ESAWAS 2022). The definition centres on deliberate state influence, but with a wide range of formal and informal sources contributing to, or impeding, the process.

In line with the above definition, compliance within the context of this study is with policy goals for universal access to safe sanitation, rather than with a given regulatory framework. Safe sanitation includes safe emptying for sanitation workers and the household and safe transport for the wider public and the environment.

The terms ‘FS E&T’ and ‘faecal sludge management’ (‘FSM’) are used for conciseness and ease of communication in this study. However, we recognise that road-transported sanitation is a more precise and less pejorative term (Strande et al. 2023).

‘Wider enabling environment’ includes the six components as described by Strande & Brdjanovic (2014): government support, legal framework, institutional arrangements, skills and capacities, financial arrangements, and socio-cultural acceptance. Regulation is itself part of the enabling environment but is considered separately here.

Reflecting the multi-level systems of regulation outlined in the introduction, ‘national regulator’ is used for whichever national authority has the primary responsibility for regulating sanitation service provision. Utilities and municipalities, or the municipal department, which are responsible for sanitation, are referred to as ‘mandated authorities’. It is recognised that mandated authorities may also be directly providing FS E&T services and/or monitoring and controlling the activities of a local private sector. Where they are acting as regulators, they are referred to as ‘local regulators’. ‘Service provider’ refers to the individuals or businesses directly involved in FS E&T.

The holistic model of business compliance, in Figure 1, shows the economic, social, and normative motives of the target group (here either the mandated authority or the service provider) and how their characteristics, capacities, and decision-making resources are impacted by external agents, environments, and events, and thereby impact compliance behaviours, considering both short- and long-term effects. The model is accompanied by a set of questions to understand each element.

A conventional (sequential) eDelphi study was used, with data collected through an online tool (Hasson & Keeney 2011), aiming for wide expert input to generate ideas and understand the level of consensus (Steinert 2009). The Delphi study design incorporated the recommendations of Beiderbeck et al. (2021) and common quality control measures, as identified by Diamond et al. (2014).

The Delphi questionnaire included fixed statements, to be scored in terms of relevance or importance, and open-text responses to add statements or provide commentary. Experts were engaged and retained with non-monetary motivation, primarily their interest in the topic area. A two-round Delphi study was used to minimise time demands and improve retention (Landeta & Barrutia 2011). The expert selection was a combination of a predefined panel and expert nomination (Okoli & Pawlowski 2004), with snowball sampling used to expand the panel until the saturation point was reached in nominations. The expert panel aims to have ‘deep level diversity’ (Spickermann et al. 2014). The panel was heterogeneous, with experts selected across multiple locations, stakeholder groups, and perspectives. No exclusion criteria were defined.

Delphi statements, given in Table 1, were developed based on established drivers and barriers for regulation and compliance (Parker & Nielsen 2017; Lerebours et al. 2022). The survey was piloted as recommended by Sheatsley (1983) and administered through Qualtrics (2020).

Complete first-round responses from 152 experts, based across 25 countries, including academics, regulators, mandated authorities, service providers, and non-governmental organisations (NGOs). The findings were summarised for the second-round survey. The retention rate was 75%, above the minimum level to consider this a valid dataset (Keeney et al. 2011). The questionnaires and the first-round summary are provided in the Supplementary Materials.

The minimum level for consensus was taken as 70% agreement across two points on a five-point Likert scale (Diamond et al. 2014). Challenge statements with consensus on agreement, and ranked within the top four challenges overall, were identified as priorities. Additional statements and commentary were coded; the results are reported for all issues raised by 10% or more of respondents. The results were checked for stakeholder subgroups of at least 20 respondents (Green & Thorogood 2004; pp. 102–104).

This study uses a subset of the data collected through the Delphi survey, using both challenge and good practice statements.

The literature review was structured using the Preferred Reporting Items for Systematic Literature Reviews and Meta-Analyses (PRISMA) statement (Page et al. 2021). Minimum requirements from Bramer et al. (2017) were supplemented using online literature mapping tools to source peer-reviewed literature. Practitioner literature was sourced from expert panel recommendations. Following screening, a total of 262 articles were reviewed and analysed, including 173 peer-reviewed papers and 89 practitioner reports.

An adapted Critical Appraisal Skills Programme Qualitative Studies checklist (CASP 2018) was used for quality assessment of the papers and reports. A thematic analysis to synthesise the full texts in Nvivo (v14, 2023) used the Delphi study results as the coding framework.

The PRISMA flow diagram and the full set of the literature reviewed are given in the Supplementary Materials. The results section includes key literature, prioritising recent academic papers with a wider geographical scope.

The results from the Delphi study and the literature review are given in Table 1, structured by each challenge, and overall good practice.

The costs of compliance for service providers: high operating costs, largely in (hard-to-monitor) transport and disposal, which increase in low-income areas.

Cost structures of service delivery were ranked as the most important barrier to increasing safe FS E&T. Responses specified that cost structures should be considered across three areas: operations and maintenance making up the bulk of expenditure and also being more difficult to finance than capital expenditure; the cost of providing safe services typically increasing in lower-income areas; and safe transport and disposal being the greatest cost and also the least visible part of the chain. Agreement with this combined cost challenge was high (85%).

There was no consensus on good practice to address this challenge, with 58% agreement on the usefulness of direct contracting of service providers by public agencies. Substantial minorities considered that the FS E&T business should be run for profit (48%) and financed through user fees (35%). A minority (<5%) considered that these challenges could be addressed through technical innovations in service delivery.

The literature largely reflects the issues raised through the Delphi study; compliance may not be feasible without material support for service providers. Despite a strong market narrative around service provision, public subsidy is necessary for universal access to safe sanitation.

Operational costs frequently make up the main cost for FS E&T services (Sainati et al. 2020). These costs are likely to increase in the future given the inherent fragility of road-based systems in the context of climate change and rapid urban development (Hyde-Smith et al. 2022). Recurrent costs are ‘an afterthought’ for policy-makers (Muzenda et al. 2022). Funding, if available, is channelled into capital expenditure, such as treatment works (Peal et al. 2020).

Viable sanitation business models are presented in the literature (Rao et al. 2016; Schmitt et al. 2017). However, profit margins are noted to be low, and businesses may only be viable if low-income areas are excluded (Wilcox et al. 2023). The additional costs to a service provider to be compliant have not been well documented in the literature and may be beyond the capacity of the small or informal businesses that make up the majority of service providers (Holm et al. 2015; Singh et al. 2022).

The challenges of difficult access, poor latrine construction quality, and solid waste disposal in low-income areas are well documented (Greene et al. 2021; Conaway et al. 2023). These challenges extend emptying time and may necessitate manual emptying, which has a higher cost than mechanised approaches, due to the greater labour requirements (Igarashi et al. 2023; Muoghalu et al. 2023). The expectation of some Delphi respondents to develop low-cost, safe sanitation services may be unrealistic (Igarashi et al. 2023). Households in low-income areas would not be able to cover these costs; public subsidy would be required in most contexts for safe services to be affordable for all (Carrard et al. 2024).

Unsafe disposal is reported as common practice, often linked to the costs of transport and disposal (Muoghalu et al. 2023). Safe disposal of FS often requires payment, contributing to economic disincentives for the service provider (UN-Habitat 2023).

The mix of incentives, pro-poor mechanisms (such as dedicated funds, tariff restrictions, or specific targets for low-income areas or households), and sanctions are recognised as sectoral good practices (Strande & Brdjanovic 2014; ESAWAS 2022). However, policy-maker reluctance to invest in sanitation and the tension between reaching universal access and operational cost recovery from user fees are widely discussed in the literature (Carrard et al. 2024; Joseph et al. 2024). There are increasing calls for greater public finance, as highlighted in the sub-section ‘Financing’.

There are typically low levels of trust between the utility/municipality and workers or enterprises providing services.

In the Delphi study, the lack of trust between service providers and mandated authorities was identified as an important barrier, with 70% agreement overall in the first round and 87% agreement on it being a key challenge in the second round. It was ranked within the top four challenges.

There was consensus (82% full agreement, 18% in agreement, but with additional commentary and suggestions) around the description of responsive regulation representing good practice in building compliance. This approach requires regulators to engage with trust and for the first regulatory responses to be non-coercive and based on support and relationship building with the target group (Nielsen & Parker 2009).

However, this appears to be a contentious point as the largest area of disagreement in good practice was around the balance of sanctioning and supporting service providers. Some respondents (7%) highlighted that sanctions and penalties should be applied more widely by the regulator, but a further 5% considered sanctions too heavily weighted in comparison to the support to service providers.

The literature largely reflects the importance of relationship building and the potential of responsive regulatory approaches but does not explicitly include trust as a decisive factor. Literature typically focuses on national regulators, rather than mandated authorities acting as local regulators.

The guidance from IWA (2021) and WHO (2018) highlights the importance of local and national regulators understanding service providers and noncoercive means, with a stepped approach taken that allows for redress and sanctions applied as a last resort. Regulators can have a critical role in building relationships with service providers (Lerebours et al. 2022; Valette & Colon 2024). Service providers have stated a desire to be regulated if they perceive the process to be fair and flexible (Christopher & Beal 2022) and studies have emphasised the importance of recognising the service providers as knowledgeable contributors rather than subjects of regulation (Gautam et al. 2021; Lawhon et al. 2023).

A gradual shift in national regulators' role, towards social and technical, in addition to economic, regulation has been noted alongside the recognition of their importance in going ‘beyond mere policing’ and supporting incremental change (UN 2017; ESAWAS 2022; WHO 2023a). More delegated and participative approaches are recorded in some locations (IWA 2022).

In documenting this evolving role of the regulator, the ‘trust’ between service providers and regulators is explicitly referenced in only a handful of articles (Lerebours et al. 2022; IWA 2022; ESAWAS 2022). In these articles, the reference to trust is included as part of a much wider discussion, for example, noting that it is a requirement for effective regulation or can build compliance, but not discussing it in depth. Similarly to the Delphi study questionnaire used in this study, trust is considered a simple concept and is not defined. Looking more widely, the literature on public health appears to consider trust as a central tenet of ways of working (UN 2017; WHO 2023b).

The service is viewed as low status (and in some places – disgusting), impacting pit emptiers and also managers and leadership in utilities/municipalities.

In the Delphi study, disgust and status as a challenge for compliance reached 72% agreement in the first round and 90% in the second round. It was ranked within the top four challenges. A minority of mandated authorities and service providers highlighted that ‘disgust’ was too strong or limited only to those directly involved in emptying.

The literature reflects the findings from the Delphi study; status is highlighted as important, and disgust is alluded to, but the challenge is largely limited to front-line service providers. There are isolated examples of the wider effects of disgust in rendering sanitation less visible.

‘Acceptance’ of FSM is part of the enabling environment outlined by Strande & Brdjanovic (2014, p. 369), and the perception of sanitation as ‘disgusting’ is noted by UN-Habitat (2023) as a block to provision of safe services. Case studies indicate how disgust can shape FS service delivery, reducing visibility (Prasad & Ray 2019), making manager positions less desirable (Grisaffi et al. 2022), and affecting service legitimacy (van Welie et al. 2019b; Cookey et al. 2020). Other papers allude to taboos that prevent stakeholder engagement (Hyun et al. 2019).

The marginalisation and social stigma faced by sanitation workers, including but not limited to pit emptiers, are well documented (UN 2012; Bhatkal et al. 2024). Alongside the challenges of stigma are examples of service providers as deeply embedded social actors and informal providers as essential to reaching the most vulnerable (Muoghalu et al. 2023; Chumo et al. 2024).

The positive effects of professionalism and service status in building compliance have been noted for both service providers and mandated authorities (Mumssen et al. 2018; Valette & Colon 2024). The wider literature incorporates making compliance visible and valued (Mason et al. 2020; ESAWAS 2021a).

Research into the motivations and priorities of pit emptiers is largely centred on occupational health risks and financial drivers, with limited literature on wider social and normative drivers (Zaqout et al. 2020; Bhakta et al. 2022; WHO 2022).

It is difficult to demonstrate the link between individual unsafe pit emptying practices and the impacts (poor public health and environmental damage).

Only 30% of respondents agreed, and 31% strongly disagreed, that it was difficult to link safe practices and impact. This challenge was also low-ranked in terms of importance.

The literature reflects the findings in the Delphi study; the links are clear but do not lead to change.

A number of trials have demonstrated the difficulty of linking sanitation interventions to health impacts, and some literature posits that this is a barrier to change (Winters et al. 2014; Pickering et al. 2019). However, many studies indicate high awareness of health risks from faecal contamination for both households and mandated authorities without any resultant change, due to the prioritisation of other benefits or services or lack of resources and capacity (Kwiringira et al. 2021; Conaway et al. 2023).

External pushes (e.g. development banks, INGOs) and internal (e.g. national or city) drivers are often different.

The initial wording for this challenge was ‘There is a strong external push (e.g. development banks, INGOs) for expanding safe faecal sludge services, however, it is a lower priority for local actors'. More than 10% of respondents disagreed and highlighted that safe sanitation was important for all actors, but there was a misalignment in priorities for implementation. Including the adapted wording, the majority of respondents (64%) agreed with this statement. However, this percentage is below the 70% required to consider it a consensus. This challenge was also low-ranked in terms of importance.

The literature appears to give a greater weight to external actors than is reflected in the Delphi study. Donor prioritisation is identified as a key driver for increased investment into FSM and the development of related policy and regulation (Hutchings et al. 2018; Sinharoy et al. 2019; Heidler et al. 2023). External drivers are identified as a barrier to the implementation of regulation due to reduced local ownership (Lerebours et al. 2022). However, local variables may be a greater determinant of access to sanitation (Francois et al. 2021; Beard et al. 2022).

A number of additional challenges linked to the wider enabling environment were identified, aligning closely with the City Service Delivery Assessment developed by Blackett & Hawkins (2019). Four additional challenges were identified by at least 10% of respondents and ranked as the most important barriers; (i) resources are insufficient and not allocated equitably, (ii) public expectations of a safe service, and willingness to prioritise this safe service, are low, (iii) there is an unclear, or actively obstructive legal and regulatory framework, and (iv) low political will and prioritisation. Linked to (ii) there was clear consensus (80%) on the good practice of changing social norms, both raising expectations for safe practices and minimum service standards.

Recommendations to add the challenge of ‘Lack of integrated planning across sectors and urban areas', were supported by the majority of respondents who reviewed the full list of additional challenges.

The low capacity of mandated authorities service providers was raised as a challenge by 5% of respondents and reflected in the consensus (88%) around the good practice of support mechanisms for service providers, making compliance easier.

The literature review confirms the issues raised through the Delphi study. These challenges in the wider enabling environment are well documented in the literature (Scott et al. 2019a; Valette & Colon 2024). This section is structured by the Blackett & Hawkins (2019) City Service Delivery Assessment.

Policy, legislation, and institutional frameworks. The human right to sanitation (United Nations General Assembly resolution 64/292) has been integrated into law for at least 52 countries (Brunner et al. 2015). There appear to be stronger normative drives for universal access and an increasing number of policies and plans to reach the poor and other vulnerable populations with sanitation services (Brown et al. 2016; Rosenqvist et al. 2016; Fuente & Bartram 2018). Despite this nominal shift in political will, incomplete, or actively obstructive, policy and legal frameworks persist, for example, outlawing manual pit emptying where there are no feasible alternatives (Sinharoy et al. 2019; Bhatkal et al. 2024). Where supportive frameworks are in place, they may not be reflected in practice (Mumssen & Triche 2017; ESAWAS 2021c).

FSM is considered to require a greater level of regulatory sophistication given the wider distribution of amorphous responsibilities to households and the private sector (Delaire et al. 2020). Regulators are noted as being positioned to influence policymakers and service providers to catalyse change (Delaire et al. 2020; ESAWAS 2021a; Muzenda et al. 2022). The lack of pro-poor mechanisms, complexity of regulation, stringency, and inflexibility are all challenges to compliance (Lerebours et al. 2021a; Narzetti & Marques 2021; Saker et al. 2022).

FS E&T has complex, fragmented, and overlapping institutional structures at the national, city, and local levels (ESAWAS 2021b; WHO 2022; UN-Habitat 2023). The sector is characterised by a high level of informality and low availability of data (Sinharoy et al. 2019; ESAWAS 2021a; WHO 2023a).

FSM is not addressed in urban sanitation plans in many locations where it is the majority option, creating a barrier to access (Scott et al. 2019b; Narayan et al. 2021; Lerebours et al. 2022).

Financing. The estimated costs of reaching universal access to safe sanitation are significantly greater than the resources allocated to the sector (Joseph et al. 2024). Funding to local governments to support scaling up safe sanitation services is often limited (Beard et al. 2022; WSUP 2022). Financing allocations may be inequitable, targeting the richest portions of the population or subsidies directed towards sewered areas rather than FSM (Berendes et al. 2017; Joseph et al. 2024). The position of sanitation as a public, common, or merit good requiring public funding is increasingly recognised, despite the rhetoric around market delivery of services (Joseph et al. 2024; Mazzucato & Zaqout 2024).

Promotion, user engagement. Multiple studies have identified low levels of demand for safe services, limiting provision and resulting in low political will (Tsinda et al. 2018; ESAWAS 2021a; Mpanang'ombe et al. 2021). Willingness to pay for services could be as low as 13% of the cost of providing safe services (Tomoi et al. 2024).

Service provision in low-income areas is often blocked by land tenure and perceptions of informal areas (McGranahan 2015; Sinharoy et al. 2019). Extending sanitation services may also be blocked due to ethnic, racial, religious, or caste discrimination (Pierce 2017). Patterns of exclusion may be rooted in stigma and continue historical or colonial inequalities (McGranahan 2015; McFarlane & Silver 2017; Kithiia & Majambo 2020). Citing market drivers of demand as a barrier may mask this stigma and promote stereotypes of the ‘undeserving poor’ (UN 2012; Bhan 2022).

Capacity, technical assistance, technology. Many service providers have limited capacity to comply, in terms of cost as noted in the sub-section on ‘Cost structures’, and also in terms of time, technical capacity, knowledge, and understanding of the rules and navigating bureaucracy (Holm et al. 2015; Mallory et al. 2021; Lerebours et al. 2022). The capacity to comply is limited by the cost of compliance, as referenced in the sub-section on ‘Cost structures’, lack of access to safe disposal sites, adapted equipment, and the physical feasibility of providing a safe service (Peal et al. 2020; Conaway et al. 2023).

For mandated authorities, extending FS E&T services requires a new skill set (van Welie et al. 2019a; Saker et al. 2022). However, decentralised sanitation services delegate responsibility to the city level, without the needed support and resources to deliver on mandates (Samuel et al. 2021; Grisaffi et al. 2022; Valette & Colon 2024).

Expectations on regulators to improve governance may be high, but they also require support, with even sector leaders reporting resource constraints (Van den Berg & Danilenko 2017; Joseph et al. 2024). In turn, there is an important role for regulators in addressing capacity gaps of service providers (WHO 2018; IWA 2021; ESAWAS 2022).

The major limitation of this study is the attempt to reduce a highly complex issue to a limited number of questions across disparate contexts. A substantial minority of respondents (10%) agreed that Challenges and responses are context-specific and cannot be generalised. The literature supports this view to some extent, that good practice is not easily transferred between locations given specific institutional history, capacity, and resource constraints (Camos & Estache 2017; Mumssen et al. 2018). This consideration has informed the scope of this study to develop questions rather than postulating good practice.

The expert panel is considered high quality but is not taken to be representative of the whole sector. More than 70% of the respondents were from, or permanently based in, locations where FSM is the majority sanitation solution. Those working for regulators, mandated authorities, and service providers made up only 35% of respondents. Using online survey tools excluded many service providers, and retention of this group was most challenging (41% retention). Mandated authorities and policy-makers also had a lower retention rate of 50 and 42% retention, respectively. Additional expert panel members were invited from these groups to address this potential bias.

Literature or expert input has been collected from 32 of the 81 countries where FSM is a majority urban solution. The literature is largely limited to capital cities or to mandated authorities that are active in addressing FS E&T and where good practice has already been documented.

The discussion is structured using the elements of the adapted holistic model of business compliance (Parker & Nielsen 2017). Each sub-section below describes the changes proposed to the revised model, shown in Figure 1, and the linked questions given in Table 2. The proposed changes to the model are discussed in light of the study findings and then contextualised within the wider regulation and compliance literature.

The most significant changes proposed to the holistic model of business compliance are to give a distinct and separate role to the (local or national) regulator in catalysing change, as shown in Figure 1, and emphasising the importance of trusted relationships between the regulator and the service provider.

Under the original model, the role of the regulator is integrated with the wider external environment and largely characterised by questions around enforced compliance factors, whether the regulator is respected, and the risk of inspection, detection, and sanction (Parker & Nielsen 2017; Table 13.1).

The revised model reflects a much greater role for the regulator in making both short-term impacts through capacity building and targeted deterrence and long-term impacts on motives through building trusted relationships with service providers. The influence of the regulator on the wider enabling environment is also emphasised. This influence is both short-term, such as advocacy for greater resourcing, and long-term, through building the prestige of sanitation services and the perception of sanitation as a human right. This change reflects the findings around trust and the role of the regulator, as well as the findings around the wider enabling environment. Questions on the capacity of the regulator and how they are building the trust of service providers are added in Table 2. Existing questions are amended to include a greater focus on building relationships and to check whether sanctions are perceived as justified and proportionate.

The regulation literature highlights the importance of considering local regulators' capacity limitations. Here, we are considering the capacity of mandated authorities to regulate FS E&T service providers. Regulations conceived and designed at the national level may conflict with existing practices and interests at the local level, mandated authorities may be more at risk of capture and cronyism, and local capacity may be weaker (Asquer et al. 2016). Sancho (2017; p. 96) highlights resources and the capacity of local government as critical institutional variables for any policy objective delivered and regulated at the local level.

Trust in regulation remains a contentious topic. There is a lack of consensus on the definition and how to build trust to support regulation (Six & Verhoest 2017). In this study, we suggest using the approach of Dietz (2011) that trust is based on perceptions of ability, benevolence, and integrity of both individuals and institutions and a willingness to be vulnerable based on positive expectations of the other.

Despite this lack of consensus around what trust is and how to build it, the importance of trust for voluntary compliance is well established. The positive effect of trust in building compliance is outlined in an extensive body of regulation and compliance literature, covering sectors of corporate compliance (Cline & Williamson 2020), tax (Owusu et al. 2021; Resnick 2021), environmental protection (Lange & Gouldson 2010), and low-status public services, such as care homes and solid waste management (Six & Verhoest 2017; Davidovitz & Cohen 2022). Trust and voluntary compliance can be undermined by threats of deterrence and sanctions for minor breaches (Lubell & Scholz 2001; Feld & Frey 2007; D'Amato et al. 2018). However, the development of trust also requires credible sanctions that demonstrate procedural justice and punish ‘known bad apples' (Feldman 2010; Lee et al. 2013; Bowen et al. 2020).

The second change proposed to the holistic model of business compliance is to widen the range of social and normative motives considered in both service providers and the external environment.

Under the original model, social and economic motives are assessed through the perceived costs and benefits, both material gain and the approval or respect of others. Economic motives, as in the sanitation sector, range from basic livelihoods to profit-making. Normative motives consider the level of acceptance of regulation, both the objectives and how these are put into practice. These motives interact with the external environment in terms of the value placed on compliance by wider society and whether these values are internalised.

The revised model places much greater emphasis on social and normative motives in both service providers and the external environment. This change reflects the findings around cost structures and low service profitability, specifically around low-income areas. It reflects the findings around low status and possibly disgust as significant challenges for compliance. This change also reflects the challenges in the wider enabling environment of stigma against both FS E&T services and unserved areas. Alternative motives valuing the public good nature of a safe service are needed.

The regulation and compliance literature from dispersed and hard-to-control sectors, such as fisheries, environmental pollution, and tax, indicate that social and normative drivers may be more important than economic drivers once basic needs are met (Thomas et al. 2016; D'Amato et al. 2018; Resnick 2021). The benefits of integrating wider behavioural theory into regulatory approaches have been highlighted by OECD working papers on regulatory policy and postulated in the recent literature (Barak-Corren & Kariv-Teitelbaum 2021; Drummond et al. 2021; OECD 2021). There are clear similarities between established behaviour change approaches used in the water and sanitation sector, such as Behaviour Centred Design (Aunger & Curtis 2016), and the social-psychological determinants of compliance identified by Braithwaite & Wenzel (2008), norms, values, identity, shame, guilt, and trust, and the three regulated ‘selves’ identified by Braithwaite (2017), looking for moral obligation, justice, and benefits or status.

The revised model is extended to incorporate the human motives used in Behaviour Centred Design (Aunger & Curtis 2016), which is in common usage in the water and sanitation sector (De Buck et al. 2017; Ross et al. 2021). These human motives and the original holistic model of business compliance have seven common aspects: hunger, comfort, and hoarding (analogous to economic motives for basic income and security), fear (analogous to deterrence), affiliation (analogous to respect and approval), status, and justice. The proposed change, therefore, adds the considerations of disgust, attraction, nurture, creation, curiosity, and play. These social and normative motives are expanded in Table 2 and considered for the service providers and for the influence of the external environment.

‘Disgust’ appears to be the most controversial of these additional motives in both the sanitation literature, as discussed under the ‘Results’ section, and the regulation literature. Create, curiosity, and play align with the motivational posture of ‘game playing’ associated with non-compliance (Braithwaite 2003) and also with positive associations of how regulated groups adopt and adapt regulation through implementation (Kagan et al. 2011; Pautz 2024). However, disgust is scarcely referenced, and the stigmatisation of individuals can increase non-compliance (Braithwaite 2017; Coker et al. 2017).

The possible wider impact of disgust and status in impeding scaling safe practices warrants further research. Given our deeply ingrained responses to faecal matter, it seems reasonable to postulate that disgust may be an inherent barrier to the governance of a sector that requires the visible handling of human waste. Disgust is noted in behavioural theory as an important issue that can create hidden costs for those in the caring and waste management sectors (Curtis 2013). Disgust is also noted as leading to a reluctance to support low-income areas (Weinrib 2018). Some writers have postulated that the lack of literature on the impacts of disgust is evidence of our difficulty in engaging with the topic (Curtis 2013).

The third change proposed to the holistic model of business compliance is to widen the understanding of characteristics, capacity and decision making resources. This aspect of the model needs to be expanded to be relevant to the wide range of service providers, the high level of informality, and the challenging context.

Within the original model, the key questions for this element included the relevance of compliance to the business, awareness and knowledge of the rules, whether rules are comprehensible, and finally, whether service providers have the capacity to comply. These questions all remain relevant. However, they need to be extended to consider the nature of FS E&T as a public good and as a precarious livelihood.

The questions related to the business plan are expanded to consider the public resources needed to enable businesses to extend into low-income areas. This reflects the finding that compliance comes at a cost likely to put pro-poor service providers out of business. Questions are added to support a focus on the feasibility and ease of compliance, considering the specific challenges for low-income areas. Additional prompts are included to include both formal and informal service providers.

The importance of inclusive regulation, which aims to improve, rather than displace, the informal sector is substantiated in recent literature on the informal economy and possibly analogous sectors such as street food (Williams 2019; Pulliat et al. 2023). The implied acceptance of the informal sector as part of reaching universal access to safe sanitation may be contentious.

The final change proposed is to extend the consideration of the external environment in the holistic model of business compliance to incorporate the wider enabling environment, as defined in established citywide inclusive sanitation frameworks.

The original model had limited consideration of the external environment beyond the risk of non-compliance being reported and the existence of informal influence over service providers.

The revised model incorporates the City Service Delivery Assessment (Blackett & Hawkins 2019) into the framework and renames the external environment to be the enabling environment. The City Service Delivery Assessment lays out a systematic process, including questions and a scorecard, to assess the wider enabling environment for citywide inclusive sanitation. In addition, further questions are added around perceptions of unserved groups, sanitation services and workforce, and the historical roots of inequality and lack of access. Allocation of public resources is also considered here, reflecting the growing understanding of sanitation as a common, public, or merit good (Joseph et al. 2024; Mazzucato & Zaqout 2024).

The importance of considering regulation and compliance within this wider enabling environment is evidenced in the sanitation literature. The wider enabling environment would be more important for FS E&T than for the commercial sector for which the holistic model of business compliance was originally designed (Parker & Nielsen 2017). There are not many regulated sectors where the only practical and feasible working practices are also illegal, as is the case for manual FS E&T in many contexts.

The next step in the development of the model would be validation with practitioner experts (Jabareen 2009). Issues for investigation would be the application of behavioural theory to the compliance model and understanding the role of national and local regulators, interrogating and refining the proposals made in this study.

Understanding the compliance responses of FS E&T service providers is critical to ensuring that the regulatory frameworks put in place achieve their intended outcomes and safeguard public and environmental health. This is the first study to adopt a theoretical compliance model for FS E&T services.

We linked challenges in FS E&T service delivery using a holistic model of business compliance. The revised model integrates the well-known challenges in the sanitation sector of cost structures, enabling environments, capacity, livelihoods, and low status. The revised model also incorporates the less-discussed challenges of trust and disgust impeding the scaling of safe FS services. We identify a critical and distinct role for the regulator and a wider range of social and normative drivers for change. The model extends the scope and depth of questions to be asked in building compliance, rather than dictating good practice. This revised model could be applied to interrogate learning from other sectors, support discussions on compliance, and identify priority challenges with mandated authorities at the early stage of implementation.

We identify four priority challenges for building compliance for safe FS E&T services at scale: low levels of trust between mandated authorities and service providers, the view of the service as low status (possibly disgusting), impacting managers and front-line staff, the costs of compliance for service providers, and the enabling environment. These challenges are not presented as definitive but are expected to be relevant across many locations reliant on FS E&T for sanitation services.

The clearest new finding from this study is around the importance of trust, between the service provider and the local or national regulator, in building voluntary compliance in FS E&T. The importance of trust in regulatory relationships is well established and evidenced in the literature across multiple sectors, including those ordinarily considered as more hard-nosed and punitive, such as taxation. The research also suggests a greater role for the regulator in leveraging these relationships as a catalyst for change, supporting the development of the sector and scaling services, rather than sanctioning non-compliance. From this study, we highlight that local and national regulators should invest in understanding how to build trust with FS E&T service providers as this is likely to reduce the need for resource-intensive enforcement.

We also identify a potentially contentious finding that disgust may be a barrier to scaling FS E&T services, making the service less visible and reducing investment. This issue and the potential of using behavioural theory as part of building compliance warrant further research.

FS E&T is the majority sanitation solution in many urban areas, frequently delivered through complex multi-layered regulation. Taking a bottom-up compliance perspective, considering the local drivers and capacity of mandated authorities and front-line service providers, would support scaling this essential public good.

The authors wish to acknowledge the support and contributions of all expert panel members. The authors would also like to thank Jamie Bartram and the WaterWISER writing workshop group for their support in the development of the article.

This study was reviewed and approved by the Cranfield University Research Ethics System (CURES/17815/2023). Informed consent was obtained from Delphi survey participants.

This research was funded by the UKRI Engineering and Physical Sciences Research Council (EPSRC grant number EP/S022066/1) through the Center for Doctoral Training in Water and Waste Infrastructure and Services Engineered for Resilience (WaterWISER).

CG was solely responsible for the data collection, data analysis, and drafting of the article. CG, AP, and PL were closely involved in the design of the work and development of the article. CG, AP, PL, SD, and KM input to the conception of the work and critical review process. All authors contributed to the article and approved the submitted version.

The data that support the findings will be available in CORD-CERES Research Repository held by Cranfield University at https://dspace.lib.cranfield.ac.uk/handle/1826/20712, following an embargo of 12 months from the date of publication to allow for completion of the linked PhD thesis.

The authors declare there is no conflict.