Please see the below 2 links ...
Published by Md. Abu Hena Mostofa Kamal, Field Coordinator at HELVETAS Swiss Intercooperation Bangladesh
Please see the below 2 links for 2 technologies to solve access to safe drinking water in your area
http://www.eindependentbd.com/home/displaypage/news_2017-07-11_7_14_b?undefined.mjjo
http://www.eindependentbd.com/home/displaypage/news_2017-10-06_6_16_b?sthash.mh11U3S6.mjjo