Editorial Perspectives: sanitation developments since ‘Pitfalls and progress’

I was fortunate to have been asked to write a perspective article in the very first issue of Environmental Science: Water Research & Technology when it launched a decade ago in 2015, titled ‘Pitfalls and progress: a perspective on achieving sustainable sanitation for all’ (https://doi.org/10.1039/C4EW00087K). It highlighted my views at the time on the main barriers to progress towards universal access to sanitation and potential pathways to overcoming them. So, what's been happening since then?

Well, 2015 also marked the end of the UN Millennium Development Goal era and the start of the Sustainable Development Goals, which we are meant to achieve in 2030. While global access to safely managed sanitation has improved, from 49% to 57% from 2015 to 2022 according to the UN, we are still a long way from the target of universal access – the rate of progress will need to be accelerated by six times to reach that target by 2030. There are still 3.5 billion people lacking access to safely managed sanitation (1.9 billion in rural settings, 1.6 billion in urban settings), and of those, 1.5 billion people still lack access even to basic sanitation services.

In my 2015 perspective article I acknowledged the (perhaps obvious, but worth emphasising) point that there are many dimensions to the sanitation challenge which go beyond simply the technical or scientific, including social, governance, and financial barriers, to name a few. The fact that we're still not making progress fast enough suggests to me that there is still a need for better multi-disciplinary approaches to sanitation implementation, research, and innovation, which consider all of these dimensions of the challenge together rather than each in isolation.

An encouraging development since 2015 is the growing momentum around particular sanitation technologies and service models, evidenced by the emergence of associations such as the https://cbsa.global/ and the https://iwbsa.org/. While no single sanitation technology or approach is going to be applicable in every situation, it is heartening to see practical knowledge and experience being shared internationally about what works and what doesn't work. It has also been fantastic to see the International Water Association emphasising the need for more of a focus on sanitation, such as through their first ever https://nssconference.org/ held in Johannesburg in 2023. Surely enhanced knowledge-sharing is going to be crucially important to accelerating progress.

During my time as an Associate Editor I also guest edited a themed collection on sanitation, which gave me a renewed sense of hope. If you haven't visited it yet, do take a look at this, as well as the other sanitation-focused articles that have been published in the journal since the themed collection ended. A key theme within the collection was the need to think of the entire sanitation service chain, not just the toilet itself – from emptying of the contained waste when the toilet is full, to transport, treatment and/or disposal of the waste – and that communities need to be fully involved in decision-making, so that cost-effective, desirable, and sustainable solutions are achieved. Resource recovery was another clear theme – viewing toilet contents not merely as a waste for disposal but potentially also an opportunity for generating beneficial products. It was also clear that there is a lot of creative thinking about innovative types of toilets, and that there are significant challenges associated with field testing them to ensure their effectiveness, acceptability, and safety, and then scaling up their use.

That said, there are many ongoing and emerging technical challenges that still require innovative thinking to move us closer to universal access to sanitation, underlain by some key questions:

• Climate-resilient sanitation. How can safe and sustainable sanitation be achieved in parts of the world that already, or are expected to, experience extreme flooding and droughts? Many sanitation technologies assume containment of waste underground and infiltration of liquid into soils, but what happens when these flood with water? Many sanitation technologies rely on water for flushing and cleaning, but what happens when the water dries up? How climate-resilient are current sanitation facilities?

• Scaling up sanitation. So, you've got a sanitation technology or business model that seems to work and that people like to use – what next? What are the market and supply chain barriers and opportunities for scaling sanitation technologies? Is the solution to scaling up access to sanitation a ‘bottom-up’ approach, by empowering local sanitation technology innovation and adaptation based on some common key principles of good practice, or a more ‘top-down’ approach based on mass-manufacturing and dissemination of standardised sanitation technologies (or a combination of both approaches)?

• Sanitation in schools and healthcare facilities. What are the special sanitation challenges in these settings, perhaps requiring different technical and user engagement approaches than sanitation in homes? How do we keep toilet facilities in these settings clean and safe in the long-run, especially in rural areas lacking emptying or cleaning services?

• Resource recovery and sustainability of sanitation chains. What is the best resource recovery strategy for different sanitation chain scenarios? What are the best resources to recover – e.g. energy, nutrients, water? Can blackwater and greywater be collected and treated sustainably to a standard that is safe for reuse, especially in water-scarce and humanitarian emergency settings? How do we bring down the operation and maintenance costs of sanitation chains in a way that maintains high standards of service provision?

• Training latrine-builders and protecting sanitation workers. Sanitation facilities often fail due to inadequate construction methods – how can effective training of latrine-builders be broadened and improved? Is perhaps more focus needed on the basics of latrine construction (e.g. the superstructure, slab, door, etc.)? Also, what new equipment and practices can improve the safety and ensure the dignity of sanitation workers, e.g. when emptying latrines and transporting waste? How can existing best sanitation practices be better disseminated to practitioners?

This is not an exhaustive list by any means, and it's important to emphasise that each of these requires contributions from all relevant disciplines, not just environmental scientists and engineers, and should consider the specific needs of groups in society who have often been overlooked when it comes to sanitation planning and implementation, e.g. women and girls, people living with disabilities, pregnant women.

Which segways nicely to the fact that later this year this journal will be calling for papers for a new themed collection focused on recent developments in water, sanitation and hygiene (WASH) research, guest edited by Dr May Sule (Cranfield University), Dr George Wainaina (Eawag) and Dr Saskia Nowicki (University of Oxford). I encourage you to contribute to this collection if you are doing innovative work in this area, especially if it includes multi-disciplinary and international collaborations and fully involves the intended end-user communities. I look forward to being inspired again by your important work.

Acknowledgements

The author acknowledges the support for his research on this topic as provided by the Royal Academy of Engineering under the Research Chairs and Senior Research Fellowships programme.

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