Changing your water usage at home can help build urban water resilience

Building water resilience involves everyone in the community and as the City of Cape Town discovered when it faced its Day Zero moment, reducing consumption is critical to manage water capacity and reduce ongoing water stress. Martin Shouler introduces the 50L Home Coalition that is tackling urban water resilience through a focus on reducing demand for domestic water, inspired by the behaviour changes seen following Cape Town’s example.


Population growth, increased urbanisation and greater prosperity has led to increasing demands for water in the home. The World Resources Institute (WRI) has estimated that domestic water demand has increased six-fold in past 50 years. This comes at a time when there is growing competition for water and by 2025, two-thirds of the world’s population may be facing water shortages. During 2017/2018 there was a period of severe water shortages in Cape Town; the so-called Day Zero provided a stark warning that we should not be complacent about the availability of water. Day Zero scenarios have also loomed over other cities such as Sao Paulo, in 2014 and Chennai in 2019.

The 50L Home Coalition, convened by the World Business Council for Sustainable Development, the World Bank’s 2030 Water Resources Group and the World Economic Forum, provides an opportunity to challenge the narrative on domestic water consumption and change increasing consumption trends by creating bold partnerships to accelerate, demonstrate and disseminate appropriate and appealing innovations to drive water efficiencies.

Water demand management has an important role in building urban water resilience. With some cities in both the global North and global South having per capita consumption as high as 400 litres per person, the 50L Home Coalition offers a focus on how we can re-think the use of water in the home and how lifestyle choices can lead to a more sustainable use of water resources. By engaging with a broad range of stakeholders, the Coalition also wants to contribute towards a more comprehensive, system-wide understanding of the complexities and unexpected challenges associated with emerging solutions such as water reuse. The interdependencies between water and other urban systems play a key role too, as reductions in water consumption are also likely to reduce the energy required to transport and heat the water we consume in our homes.

Arup has learned at close hand how water scarcity is impacting the way we live. Through the City Water Resilience Approach (CWRA) work supported by The Resilience Shift, we helped Cape Town develop its long-term water strategy; Day Zero necessitated the city authorities and citizens to re-appraise how water was used in the home and this experience has created a new imperative around using water wisely. As part of the CWRA, Arup brought together key stakeholders in the city from citizen groups to the water authority and from energy utilities to the city authority. We were able to use the OurWater digital engagement tool to map the actors in the water cycle including identifying ‘overlaps’ and ‘underlaps’ in responsibility. This was the first step in establishing a shared consensus for developing a holistic water strategy.

There is a growing realisation that there needs to be a new water wise paradigm. However, there are challenges to overcome including user acceptability, behavioural change, retrofit, the need for appropriate regulations and technical standards, and issues to mainstream new technology. The 50L Home Coalition is looking to build a partnership of companies, policymakers, innovators, and researchers working together to define an appealing path towards a daily domestic per capita consumption of 50L in cities whilst ensuring access to affordable and safe water for all.

For this to happen, new technology will be required including water re-use and water efficient fittings and appliances. Supporting new collaborations to enable a broader innovation ecosystem is also a key factor; Arup has been engaging with innovators and the supply chain through its Wet Networks and Venturi portal platform. We see that collaboration is an important ingredient in helping to transform how we value and use water.

The wise use of water in our homes can contribute to a water resilient future.


Martin Shouler and Louise Ellis are steering The Resilience Shift’s development and support of the City Water Resilience Approach to building urban water resilience, currently being implemented in Addis Ababa. Martin is a Water Engineer  and Urban Resilience Practitioner as well as Arup’s London Water Leader.

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