The regulator in Musapur, Companiganj of Noakhali, has broken due to water pressure from upstream in India's Tripura as well as Comilla and Feni in Bangladesh.
The regulator broke at 10am on Monday due to the excessive water pressure, causing panic among the locals, with thousands heading to shelters for refuge.
Locals said while the floodwaters recede during low tide, saline water may now enter the locality during high tide, which may lead to further flooding in the area and a freshwater crisis due to increased salinity.
Bangladesh Water Development Board Executive Engineer Munshi Amir Faysal said: "This could lead to the intrusion of saline water into the area."
