how can we remove water pollution of river

in normally water are pollution in plastic matter product are throe in water .

in cow and other animal are washing  to water are pollution. 
normally in city area maximum plastic made product are thou in water that is main source of water pollution  
effect of water pollution
water pollution are most effect in water living animal. becouse all the animal are need to pure water to their survival. 
then other living animal becouse they also are need to water in threat survival.