Well, water quality is increasingly in the news. There is a political dimension to this as unfortunately the decisions made by MPs can often have a greater environmental impact than the decisions made by you and I, so influencing them is important. Education, reporting and films like Jack's do this indirectly, and practical action at a local level can also be effective, but only government can influence the water companies' and legislate against pollution. Maybe inviting people with influence in national and local government to events like this might be more effective than just writing a letter to your MP. People who use waterways and the coast recreationally are also concerned about water quality, so building alliances with them might be another useful strategy.