Lake Windermere in the Lake District is a UNESCO world heritage site visited by millions of people a year but much of it is polluted with the bacteria found in sewage - according to a survey by volunteers. Citizen scientists took more than a thousand samples from the lake over two and a half years and found levels of harmful bacteria and phosphorous which failed water quality standards. The government said it was committed to ending sewage pollution in Windermere entirely. | Channel 4 News