A launch leaves a trail of bubbles in the water of the Buriganga river which has turned dark from pollution on Sunday, Mar 21, 2021 on the eve of World Water Day. Photo: Asif Mahmud Ove

A launch leaves a trail of bubbles in the water of the Buriganga river which has turned dark from pollution on Sunday, Mar 21, 2021 on the eve of World Water Day. Photo: Asif Mahmud Ove

Vessels leave trails of bubbles in the water of the Buriganga river which has turned dark due to pollution on Sunday, Mar 21, 2021 on the eve of World Water Day in this photo clicked from Bangladesh-China Friendship Bridge. Photo: Asif Mahmud Ove

Vessels leave trails of bubbles in the water of the Buriganga river which has turned dark due to pollution on Sunday, Mar 21, 2021 on the eve of World Water Day in this photo clicked from Bangladesh-China Friendship Bridge. Photo: Asif Mahmud Ove

A launch leaves a trail of bubbles in the water of the Buriganga river which has turned dark from pollution on Sunday, Mar 21, 2021 on the eve of World Water Day. Photo: Asif Mahmud Ove