A Perfect Planet

BBC1, 8pm We’re all aware that water is vital for the survival of life on Earth. But as most of it exists in the sea, which is too salty for many species, the planet’s reserves of freshwater are vitally important. As this terrific series continues, David Attenborough reveals how its uneven distribution has helped form the landscape, from deserts, where it’s scarce, to rainforests, where it’s available in abundance.