Dialogue between two friends on water pollution
Sujon: Hello Jahangir! How are you?
Jahangir: I am fine. What about you?
Sujon: I am fine too. But I am somewhat worried about water pollution. 
Jahangir: Yes, it is very alarming that the water of canals, rivers, and tanks is getting polluted day by day.
Sujon: Exactly! This polluted water causes much harm to us.
Jahangir: But man is mainly responsible for water pollution. They pollute water by throwing waste into it.
Sujon: Yes, farmers also use chemical fertilizers and insecticides in their fields. Rain and floods wash away some of the chemicals.  
Jahangir: Right you are. And these chemical fertilizers and insecticides get mixed with the water of canals, ponds, and rivers, and thus pollute water.
Sujon: Mills and factories also pollute water by the waste materials.
Jahangir: Exactly! Leaking of oil from water vehicles, dead bodies, and rotten debrises of animals and plants also contribute much to water pollution.
Sujon: Besides, germs of diseases and insanitary latrines are other factors that pollute water.
Jahangir: So, it is high time to stop water pollution. But how can we prevent water from being polluted?
Sujon: Water pollution can be prevented in many ways. But the main way is to make people aware of the importance of pure water.
Jahangir: I am agreed with you. There is no alternative to make people aware of the bad effects of water pollution.
Sujon: Thank you very much for discussing such an important issue.
Jahangir: You are most welcome. See you again.