Safe Water 

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 started the climate project to provide communities in Sarankhola with access to safe water through the environmentally friendly method of Solar Water Disinfection (SODIS) with HELIOZ’ frugal innovation, the UV indicator WADI. Currently 5000 households (25,300 people) benefit from the HELIOZ technology. In response to local demand and available settlement networks, the “sharing method” was integrated into the project supplying an additional 2,600 people.

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


5000 household switched to water treatment with SODIS and WADI. In the reporting period, the majority (97 %) 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 87 % of households storing the water for up to 48 hours. On average each household disinfects 26,4 litres of water per day. 98 percent of users have positively indicated a reduction in waterborne diseases, saving every household about 14 USD per year in medical costs. Furthermore, 16 school days and 13 workdays are additionally available to households due to disease reduction. The intervention also triggered the establishment of 100 disability inclusive 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)
  • 10,625 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

  • 5000 WADIs
  • 5 FTE positions established in Bangladesh (community facilitators)
  • 1,200 group meetings / year
  • 100 women groups
  • 35 people with disabilities (PwD) integrated in the project