In the 2022 Policy Address, the Government set a target of reducing by half the pollution loading at stormwater outfalls with serious pollution problems on both sides of Victoria Harbour, in particular at Tsuen Wan, Sham Shui Po, and Kowloon City, by the end of this year.

Thanks to the combined efforts of the Buildings Department, Drainage Services Department (DSD) and Environmental Protection Department (EPD), as of the second quarter of 2024, the pollution levels not only met but exceeded the target, dropping by about 80%.

A recent survey by the EPD at the Tsuen Wan waterfront showed that 75% of respondents noted an improvement in odour levels, with nearly half of them reporting a significant improvement.

Moreover, the concentration of hydrogen sulphide, a key indicator of odour intensity, has dropped significantly by about 80% from April 2022 to this August in the area.

“Unlike past years, in the morning, it was very smelly. The wind is so fresh today. I don’t smell anything,” said a Tsuen Wan resident, who has been living in the area for two years. 

Misconnections of sewage pipes to the stormwater drainage system in old districts can cause major odour problems because the sewage is then discharged through stormwater drains to the three main underground box culverts in Tsuen Wan District, and eventually flows out to the waterfront.

The EPD plays a crucial role in locating the pollution sources.

“We first collect and analyse water samples to identify areas with potential pollution sources. We then, based on the drainage map of the DSD, trace the exact location of misconnection from downstream to upstream through dye tracing, pipeline closed-circuit television robots and other smart tools,” Environmental Protection Department Senior Environmental Protection Officer Fanny Wong explained.

The Buildings Department then steps in to follow up with misconnections.

“Once we confirm there is misconnection in private buildings, we will issue an order to the liable party or the owners of the building, requiring them to rectify the situation,” said Buildings Department Senior Structural Engineer Sonny Kan.

Similar misconnections exist in public sewers, which are followed up by the DSD, which also expands infrastructure to accommodate population growth and sustainable development in Tsuen Wan.

“The DSD is constructing approximately 7km of sewers through public works projects. The project started in July 2020 and the progress is satisfactory. The project is anticipated for completion in phases by mid-2026,” Drainage Services Department Senior Engineer John Leung added.

Between 2022 and the third quarter of 2024, 36 cases in Tsuen Wan have been rectified, addressing 89% of its total pollution. Sham Shui Po resolved 16 cases, tackling 66% of its total pollution, while Kowloon City rectified 32 cases, eliminating 99% of its total pollution.