The calculated distance (air line) between Hung Shui Kiu and Kowloon is approximately 15 miles respectively 24 kilometers.
By car or train, the actual journey to Kowloon is certainly longer, as only the direct route (as the crow flies) between Hung Shui Kiu and Kowloon has been calculated here.
Air line (approximately)
24 kilometers
13 nautical miles