The Kowloon Byewash Reservoir was completed in 1931. Its completion was reported in the Public Works Department's Annual Report for that year:
141. Water from the new Byewash Dam became available on 16th January, 1931. This dam which forms the connecting link between the Kowloon Reservoir and the Shing Mun Supply has a capacity of 185.50 million gallons and provides a much needed addition to the mainland storage.