Sewage-contaminated drinking water causes serious illness such as diarrhoea and other gastrointestinal and stomach problems – putting millions of lives at considerable risk each year.

Globally, there are 1.7 billion cases of diarrhoea annually resulting in over 0.5 million deaths of children under five years old (World Health Organization’s 2017 fact sheet). The last two decades have seen significant improvements to drinking water supplies across the developing world, thanks to the efforts of governments, communities and NGOs. But new research has shown that despite good progress, millions of slum dwellers are still exposed to considerable risk because water supplies are being contaminated by human waste just metres from the family home.

Researchers working in Dhaka – the capital of Bangladesh,  and Dar es Salaam – the commercial capital of Tanzania – have launched an experiment to test the best way to ensure water remains safe to drink as it makes its final ‘100 metre’ journey from community standpipes to homes.

Unserved by sewerage systems, slum-dwellers rely on toilets that drain into poorly constructed septic tanks or pits. The community-based water dispensing facilities commonly lack the integrity needed to prevent localised contaminants entering the drinking water being supplied. Settlements are commonly located on low-lying and poorly drained lands, and the local population often lack adequate provisions for safe disposal of sewage – so resulting in a heightened risk of contamination of the treated water.

Dirty and open buckets, unwashed hands, insect and rodent vectors also contribute to water contamination as it is carried back into the house, causing ill-health and widespread suffering.

Funded by the British Academy’s Sustainable Development Programme, the group of world-leading scholars, practitioners and entrepreneurs attempting to tackle the problem is led by the UK’s Lancaster University-based Bangladeshi scientist – Dr Manoj Roy.

He said: “Urban, national and increasingly global architectures for sustainable development are falling short, just metres before the ‘finish line’. This has severe consequences for public health. It also denies politicians and their development partners the opportunity to celebrate and take credit for providing treated water to most slum settlements. Much progress has been made in delivering water to poorer communities. But this good work will fail to deliver real benefits as long as these communities remain unserved by sewerage systems.”

Working in an interdisciplinary manner linking social sciences with environmental sciences is an essential aspect of this research. The team’s UK lead for the water quality component of the work Dr James Rothwell of The University of Manchester said: “Our comprehensive programme of water quality monitoring will provide crucial evidence to identify the sources of the drinking water contamination and the impact of our settlement interventions.” 

The team has been conducting research in slum communities in Bangladesh and Tanzania since 2013. This work -supported by the UK Government through the Ecosystem Services for Poverty Alleviation (ESPA) research programme - aimed to understand the dilemmas of basic service provision for the poor, and find ways of resolving them.

In this new phase of their work, the researchers are evaluating a range of approaches to improving sanitation and reducing contamination of treated water in eight varied communities in Tanzania and Bangladesh to see which approaches are the most effective. The project focusses on the final leg of the drinking water journey – the relatively short space from the point of collection to people’s homes that the team describes as the ‘Last 100 Metres (L100M)’. Watch the film here.

Their research findings will be used to inform government and NGO policy; to transform infrastructure and practice; and to make a huge difference to the lives of millions of slum dwellers around the world.

The L100M team is working with several international and local NGOs, civil society ‘think tanks’ and business partners to harness this potential. These include BRAC Tanzania, British Water, the Centre for Science and Environment (CSE) India, Dushtha Sashthya Kendra (DSK) Bangladesh, and WaterAid Bangladesh (WAB).

Lancaster University co-investigators are Professor Nigel Clark and Dr Nick Chappell. Professor Clark said: “We need very carefully designed experiments to ensure that any beneficial effects of our interventions to water quality and human heath are credible academically and with the communities themselves.”

The Last 100 Metres: Safeguarding Potable Water Provisioning to Urban Informal Settlements is sponsored by the British Academy Sustainable Development Programme as part of the Government’s £1.5 billion Global Challenges Research Fund.

The team includes: four Bangladeshi organisations (BRAC University, Dhaka University, Dushtha Shasthya Kendra [DSK], and WaterAid Bangladesh); one Indian organisation (Centre for Science and Environment [CSE]); two Tanzanian organisations (Ardhi University and BRAC Tanzania); and three UK institutions (Lancaster University, The University of Manchester and British Water).