Clean lakes for a clean future
Scaling up nature-based solutions to tackle wastewater and human waste pollution in Bangladesh's urban lakes.
In the informal, high-density, low-income settlements in Bangladesh, tens of thousands of people, including children, face daily struggles to access basic water and sanitation facilities. These challenges leave them highly vulnerable to communicable diseases. But the problem extends beyond these communities. Local authorities are grappling with the provision of comprehensive and safely managed sanitation services needed to maintain a clean, sustainable environment and to protect urban lakes, often contaminated by tonnes of untreated human waste and other pollutants. This poses an additional threat to the survival and wellbeing of children in Bangladesh.
Selina, a 43-year-old mother of four, lives in the Korail slum near the heavily polluted Banani Lake in Dhaka. The lake is choked with garbage, including human waste, as Selina explains, “all the garbage from the slum, even from places far away, is dumped here.”
“Sometimes we clean the drains ourselves or hire someone with our own money. Otherwise, a lot of mosquitoes are born here. And it stinks all the time because all sorts of rubbish - polythene, clothes - is thrown into the drain that goes to the lake.” - Selina, Korail resident.
The monsoon brings additional challenges to settlements like Korail, where flooded streets and clogged drains turn stagnant water into a breeding ground for mosquitoes. Selina’s older sons have had dengue fever, a mosquito-borne disease, that kept them out of school for long periods of time, impacting both their education and the family’s income.
For years, untreated waste from toilets in the Korail slum was discharged directly into drains, which flowed into the city's waterways and further polluted Banani Lake.
In 2023, UNICEF's Bangladesh country office with the financial support from Gates Foundation began collaborating with local government to pilot wastewater treatment systems that use natural processes — sedimentation, biological activity and sunlight — to treat household wastewater. These solutions ensure the water released does not pollute the environment, while also providing environmental benefits and promoting healthier communities for children and their families.
Currently, these nature-based solutions help treat the wastewater of 862 households, benefiting 4,300 people, including children. The system uses tanks and a solar pump in an advanced anaerobic-anoxic biological process, coupled with beds of gravel and activated carbon to reduce particulate matter and water coloration. Additionally, 100 households are using a containerized treatment tank that uses treated water for flushing toilets, reducing pressure on the Dhaka Water Supply and Sewerage Authority.
Having proven successful, these solutions have been identified by UNICEF as promising innovations for scaling. The Sustainable WASH Innovation Hub, in collaboration with the Government of Denmark and the Gates Foundation, is working alongside UNICEF’s country office in Bangladesh and local authorities to introduce these nature-based wastewater treatment solutions across all urban water bodies in Dhaka. To ensure sustainability, the Dhaka North City Corporation plans to continue operating and maintaining the systems after handover.
"My children and I now live in a cleaner and safer environment," says Selina, adding that her family now benefits from reduced water and sanitation charges and spends less time collecting water for flushing, thanks to the treated water.
Immediate problems demand immediate action, and innovative solutions provide the necessary accelerated response to address urgent issues. In the water and sanitation sector, innovation is key to ensuring a thriving, healthy future for all children.
Recognizing the critical role of innovation, UNICEF is enhancing its capacity to develop and scale innovative solutions like the ones in Dhaka across every country where it operates. With the support from the Government of Denmark, the Sustainable WASH Innovation Hub is envisioned as a global center for developing, accelerating, and scaling transformative, climate-resilient solutions for universal and equitable access to water and sanitation.
