Mexico's capital often floods during the rainy season, but paradoxically, it's also running out of water. A large and growing population, along with crumbling infrastructure and the effects of climate change - are increasingly putting a strain on the city. We meet the army of scientists, activists and urban planners trying to solve this problem - and rethink Mexico City’s relationship with water - including the scientist using plants to clean sewage water and the architect who has designed a park that absorbs excess rainwater.Presenter: Myra Anubi Reporter/producer: Craig Langran Series Producer: Jon Bithrey Editor: Tom Bigwood Sound mix: Hal Haines(Image: Alejandro Alva in Cuautepac wetland area, Mexico City, BBC)