The freshwater realm in Singapore is surprising rich; despite the small size of the island, over a century of human impacts and a host of other problems. While clean drinking water is an important national concern; the stream, swamps, waterways and reservoirs in Singapore nevertheless also contain many native species of plants and animals that represent the original natural heritage of the island. In the third part of this series, the “Private Lives” of the denizens of Singapore’s waterways – both native and non-native, are examined; and the many challenges facing this key ecosystem are discussed.