The fire was brought under control by three firefighting units
Sunday afternoon's accident at Siddhirganj left two others injured.
The water tank’s wall collapsed killing Jhorna Akter, 50, on the spot, Siddhirganj police OC Md Alauddin said.
Abdur Rob, 80, died while being taken to the hospital.
Two others, Suraiya Akter, 8, and Doli Akter, 7, have been admitted to Dhaka Medical College and Hospital.