Thousands of people will march on London on Sunday at a family-friendly rally to highlight the importance of clean water in their lives. The BBC speaks to residents near one rural waterway, which scientists found had the second highest levels of active pharmaceutical pollution in the UK.

"You'd think as a country we would be able to look after our most pristine landscapes", says cold water swimmer Jo Broughton.

Jo Broughton has not dipped even a toe in Tideswell Brook, in the heart of the Peak District National Park, since August.

One of the reasons lies in the findings of a study that discovered the brook had the second highest levels of active pharmaceutical pollution in the UK - drugs such as antidepressants and antibiotics were detected in the water.