A report issued in the United Kingdom said that use of plastic bullets over water cannon was justified because "Water cannons are inflexible and indiscriminate", although several people had been very seriously injured by plastic bullets.
Water cannons designed for riot control are still made in the United States and the United Kingdom, but most customers are overseas, particularly in Africa and parts of Asia.
Thanks, Octavious, I know that they are used in France and Germany, but it seems that they are less used in countries where there is a free press than elsewhere. Whether or not that is relevant or not, I don't know.