Most stormwater drains will enter a waterway. The waterway might be the sea or it will be a stream or river that will empty into the sea. Stormwater will carry litter and other pollution with it. The amount of litter that comes out of drains is directly proportional to the amount of other pollution. So beaches that have a lot of litter washed in from stormwater will also be the very polluted. However, many councils use tractors to rake up the litter so now you can’t tell.