Waste not: New UN-Water report examines the potential of wastewater

Mitigating and adapting to climate change through what goes down the drain

Water collection from a hand-dug well near Chiana, Ghana. Axel Fassio, CIFOR
22 March 2020
Sandra Cordon

Once you flush the toilet or pull the plug on the dirty dishwater, you probably don’t give your wastewater another thought. But what if you learned that this water could actually be a potent tool in the fight against the climate crisis?

That lesson is being practiced in Jordan, Mexico, Peru and Thailand, where novel wastewater treatment projects are helping tackle climate change by cutting energy consumption, reducing water loss, and recovering energy and nutrients in the waste. So says the United Nations World Water Development Report 2020, which cites the projects as it examines how better water management can not only help nations face climate change.

Despite its far-reaching potential to confront the climate change crisis, water is all too often overlooked in global climate talks – and in funding for crisis mitigation work, says UN-Water’s flagship report on water and sanitation issues, launched in conjunction with World Water Day on 22 March 2020. In fact, just 2.6 percent of climate finance in 2016 went directly to water management, notes the report, which was coordinated and produced by UNESCO for UN-Water.

“Water can support efforts to both mitigate and adapt to climate change,” said Audrey Azoulay, Director-General of UNESCO. “Yet the word ‘water’ rarely appears in international climate agreements.”

The case studies showed that an urban project in Cusco, Peru reported a 34 percent reduction in greenhouse gas emissions from water and wastewater through the Water and Wastewater Companies for Climate Mitigation project; Thailand cut relevant emissions by 32 percent. That project has developed a tool to help water and wastewater utilities assess greenhouse gas emissions and mitigation opportunities, while assisting the affected utilities in reducing thousands of tons of CO2-equivalent emissions as they save money and improve quality of service.

“Ignoring water’s role in climate change adaptation and mitigation, and failing to embrace the opportunities… is certain to derail any significant progress towards solving either crises,” warns the report.

More efficient wastewater treatment could help reduce GHG emissions by reducing energy inputs, and produce biogas as a source of renewable energy, says the UN-Water report. Reuse of untreated or partially treated wastewater can reduce the amount of energy associated with water extraction, advanced treatment and, in cases where wastewater is reused at or near the release site, transportation costs.

Water and wastewater utilities can have large energy footprints, “so there is significant mitigation potential in increasing both water and energy efficiency, as well as in recovering energy, water and nutrients from wastewater streams,” says the report, which provides decision-makers with knowledge and tools to develop sustainable water policies.

Water also helps mitigate climate change in other ways. Wetlands offer a double punch by retaining the largest carbon stocks among terrestrial ecosystems – storing twice as much carbon as forests – while offering multiple co-benefits, including flood and drought mitigation, water purification and biodiversity. “(Wetlands) restoration and conservation is of critical importance,” said the report, part of a UN-Water series that focuses on a different theme each year.

Just over half the world’s population doesn’t have access to safe sanitation, yet water management and sanitation remain “grossly underfunded,” says Richard Connor, lead editor of the report. “There’s a simple reason for that,” says Connor. “Everybody wants water to come into their home. But once they flush it, they don’t care. It disappears; it’s not their problem anymore.”

Yet efficient use of water, including wastewater, is vital to achieving many of the Sustainable Development Goals (SDGs), particularly SDG 6 calling for clean water and sanitation. Climate change already severely affects the availability and quality of water for basic human needs, “threatening the effective enjoyment of the human rights to water and sanitation for potentially billions of people,” the report emphasizes. Approximately 4 billion people already endure severe water scarcity for at least one month per year; that will increase by 2050 when over half the world’s population will be living in water-stressed regions.

“Through wastewater, you can directly contribute to achieving the Paris Agreement, sanitation, and the SDGs,” says Connor. “It’s a win-win-win.”


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