The existing Shek Wu Hui Sewage Treatment Works (SWHSTW) has been operating for 30 years, treating sewage generated from Sheung Shui, Fanling and adjacent districts. The design capacity of the existing SWHSTW is 93,000 m3/day. After sewage treatment and ultra-violet disinfection, the treated effluent is discharged to Ng Tung River.

In 2016-2017, sewage treated by SWHSTW, on average, could reach 84,000 m3/day, which is approaching its design capacity.