University of Bristol - Historical Photographs of China reference number: NA16-108. Image from an album in The National Archives referenced as ‘HONG KONG 3. Views of Hong Kong from the 1860s to the 1920s' (CO 1069-446). According to the Hong Kong Observatory, the highest record of daily rainfall ever recorded in Hong Kong, is 534.1 millimetres - the 19th July 1926 rainstorm. During the storm, a huge boulder weighing about 3000 tonnes crashed into the No. 3 Pumping Station at Pokfulam, killing four workmen. See https://www.hko.gov.hk/en/blog/00000135.htm. See NA16-109 (another photograph of the Waterworks Pumping Station at Pokfulam Road).
Damage caused by the 19th July 1926 rainstorm, Waterworks Pumping Station, Pok Fu Lam Road (薄扶林道), Hong Kong
Black and white photograph
The National Archives, London