Bangladesh currently ranks 135th according to the Human Development Index 2019 (HDI value: 0.614; rank 135/189). The coastal belt of Bangladesh is highly affected by anthropogenic climate change and limited access to safe water sources. The main water sources for the project beneficiaries are surface water in the dry season and rainwater harvesting in the dry season.

Safe Water

In 2017, HELIOZ launched a climate project in Sarankhola, Bangladesh to initially provide 4,100 households with access to clean water through the environmentally friendly method of solar water disinfection (SODIS) using HELIOZ's innovation, the UV indicator WADI. Within the last four years, the project has been scaled up twice, with the latest addition of additional households in early 2021. Today, more than 39,150 people (7,115 households) have gained access to safe drinking water to meet their daily needs. Increased demand for carbon credits from high-impact projects has supported the expansion of the project area to meet continued requests and interest from neighboring households and villages of WADI users.

Implementation Partners: Centre for Disability in Development & Voice of South Bangladesh

Project Region: Sarankhola Upazila, Bagerhat District

Climate Action

More than 10,600 carbon credits/year are generated for the voluntary market through this project. The emission reduction is monitored and certified in cooperation with the University of Natural Resources and Life Sciences Vienna (BOKU). Prior to the start of the climate project, 97 percent of households depended on the basic method of water treatment through boiling on simple clay stoves, using around 320 kilograms of firewood per month (Baseline Report. BOKU gW/N, 2018).

Project Area Bangladesh, Sarankhola Upazila
Project Start 2017
Tons of CO2 savings per year 15,000
Target Group (households) 7,115

Sustainable Development Goals


7,115 household switched to water treatment with SODIS and WADI. In the reporting period, the majority (99,6 %) of households are using WADI every day (5-7/week) in the dry season, shifting to usage rate of 3-4 days/week in the rainy season by 88,2 % of households storing the water for up to 48 hours. 94 percent of users have positively indicated a reduction in waterborne diseases, saving every household about 14 USD per year in medical costs. In the reporting period, over 36.9 million litres of drinking water were supplied overall. The intervention also triggered the establishment of 140 women groups that meet monthly.

User Rating

The WADI technology has been rated on average 4.8 out of 5 (1-5 scale, 5 being the highest) with all 200 interviewees sharing that they would recommend WADI to others. The product demand increases continuously. Currently 760 additional households in Sarankhola have voiced their interest in WADI.

Project Resilience - COVID-19: The COVID-19 pandemic and associated restrictions have negatively affected the socio-economic situation of Bangladeshis due to i.a. loss in income and access to education. The economic situation of the project’s beneficiaries was heavily impacted: 98 % stated a reduction in household income and 79 % struggle due to increased food costs.

The flexible and tailor-made project design allowed for immediate inclusion of COVID-19 awareness messages in the WASH programme. In addition, an increase in sharing of disinfected water with neighbours was documented, especially for preventative handwashing with safe water.

Key Numbers 

  • 27,900 beneficiaries (BOKU: incl. 2600 Sharing Method)
  • 15,112  t CO2 / year
  • 51.9 Mio. liters of disinfected water / year
  • 1,3 tons firewood saved per HH / year
  • 98 % of beneficiaries experienced reduction in waterborne diseases


Input | Output

  • 7,115 WADIs
  • 7 FTE positions established in Bangladesh (community facilitators)
  • 1,159 group meetings / year
  • 140 women groups
  • 355 people with disabilities (PwD) integrated in the project