Kau To Hang (Chinese: 九肚坑) is a river in Sha Tin District, New Territories, Hong Kong. Its source starts near Cheung Lek Mei, inside Tai Po Kau Nature Reserve. It flows eastward past Nim Au, Ma Niu, Kau To, collecting minor streams on the way. Finally, it empties into Sha Tin Hoi, part of Tolo Harbour.