This video highlights one of the problems facing London's urban waterways. Shot on the Silk Stream at Rushgrove Park in Colindale. The stream flows into the Brent Reservoir, then into the River Brent, before running into the River Thames upstream of central London. Although this leak had stopped last time I was there, London's waterways suffer from pollution from breaks in the sewer system and particularly from residents illegally plumbing their domestic sewer systems into storm drains that run straight into the rivers. This is probably something that the local authorities and the Environment Agency should be doing more to combat.