Infrastructure and service approaches for greywater management in informal settlements

An increased focus on sanitation service approaches and faecal sludge management in recent years has taken attention away from the need for better integration of sanitation with other basic urban services, including drainage, in low and middle-income countries (LMICs). Increasing storm events and improvements to piped water supply has meant higher volumes of domestic greywater (wastewater from cooking, cleaning, and bathing) and stormwater runoff is generated. In informal settlements, existing water, sanitation and hygiene (WASH) infrastructure is often badly designed and poorly maintained, creating many added challenges such as: attraction of rats/mosquitos which carry disease, wastewater mixing with solid waste, environmental pollution and low level flooding; all of which exacerbate surface water accumulation and drainage issues further.

In LMICs inadequately managed stormwater, excreta and greywater is known to be detrimental to the environment, particularly to rivers, lakes, and groundwater. Despite the contributions and implications of all three wastewater streams, academic literature predominantly focuses on stormwater and excreta but excludes greywater - presenting a clear research gap. In dense urban areas, greywater is as much of an issue as excreta and stormwater, as such greater research that discusses both the challenges and contaminants associated with greywater is required.

Similarly, numerous practitioner-led projects related to urban drainage already exist, however they typically focus on stormwater management and consider issues such as increased flood events and infrastructure design or capacity - ignoring greywater. Also, community knowledge, attitudes and practices related to drainage have also been collated, however there is limited integration of these areas. As many environmental and public health issues are associated with a lack of drainage infrastructure, future work must consider solutions and approaches that incorporate and understand the contribution of greywater. For these reasons, it is imperative that greywater is given greater priority in WASH agendas; otherwise continued exclusion might weaken the overall benefits gained from alternative investments in WASH infrastructure.

To address these outlined challenges and knowledge gaps, the main aim of the research is to increase understanding of greywater management issues in urban informal settlements. By adopting an applied research approach and adhering to the principles of responsible research, the following objectives are proposed: (1) Review the implications related to a lack of adequate greywater disposal infrastructure; (2) Investigate relevant stakeholder perspectives and barriers related to greywater management; (3) Determine and evaluate if any new or existing technical or service-based solutions are appropriate for greywater management in informal settlements; (4) Identify and develop potential infrastructure or service-based approaches that would support inclusion of greywater in urban WASH agendas.

To achieve the overarching research aim, a mixed methods research approach will be adopted, and include: interviewing residents, decision-makers and key stakeholders; observing behaviour and practices within informal settlements; and collecting wastewater samples - prior to and after treatment for further laboratory testing. Subsequently, to contextualise the research, the data obtained will be analysed to create a comprehensive case study that addresses both infrastructure and service-based aspects relating to greywater management in the chosen fieldwork location.

Furthermore, by engaging with communities, additional stakeholders and an in-country impact partner for the duration of the research, the primary outcome of the PhD is to develop appropriate guidance that informs and encourages residents and decision-makers to manage greywater effectively by implementing appropriate technical or service-based solutions.

Water-WISER will train a cohort of 50 British research engineers and scientists and equip them to work in challenging environments both in the low-income settings of rapidly growing poor cities and in the changing urban environment of the UK, Europe and other regions with a historic endowment of aging infrastructure. The vision is for a generation of engineers with the skills to deliver the trans-disciplinary innovations needed to ensure that future water, waste and sanitation infrastructure is resilient to the stresses posed by rapid urbanisation, global climate change and increasingly extreme natural and man-made disasters. Our alumni will address the urgent need to re-imagine urban spaces as net contributors to ecological and environmental well-being rather than being net users of vital resources such as energy, nitrogen, phosphorus and carbon. These new leaders will be an essential resource if the UK is to deliver on its commitment to the United Nations' Sustainable Development Goals (SDGs), particularly SDG 6 which calls for universal access to safely managed water and sanitation services, within planetary and local ecological boundaries. This next generation of research engineers will enable UK-based engineering consultancies, manufacturers, and utility companies to grow their share of the expanding global market for water and waste services, for example; in the water services industry from 3% to 10% (an increase of £33 billion per annum) by 2030, and attract significant inward investment.
The research which Water-WISER cohorts enable will form the basis of new innovations in the design and delivery of resilient infrastructure and services. Innovations developed by Water-WISER graduates will inform how growing cities are designed and built in the global south and will be used to inform the re-engineering and replacement of the aging infrastructure on which the UK's water and waste services are currently reliant. Our alumni will form the new generation of leaders who will play a central role in securing a larger share of the international water and waste management consultancy market to UK consultancies. The network of expertise and skills created by Water-WISER will enhance potential for collaborations between major UK players (for example strengthening links between UK consultancy, the Department for International Development, and leading UK water agencies such as WaterAid and Water and Sanitation for the Urban Poor) and between UK companies and partners in the global south including international investors such as the World Bank, European Investment Bank, African Development Bank, Asian Development Bank, Inter-American Development Bank and the International Finance Corporation. Graduates of Water-WISER will enter industry, academia and development agencies having spent a substantial period (minimum of six months) embedded in an industry or development partner organisation delivering their field-based research. Water-WISER students will thus gain a unique combination of trans-disciplinary training, field experience and cohort networking; they are destined for leadership roles in UK and international engineering and development consultancies, academia, international development banks, international agencies such as the United Nations and international non-governmental organisations.