Drainage Services Department

Dye Test Inspection for Submarine Outfalls

 

Submarine outfalls are used for discharging treated sewage from DSD sewage treatment plants into the sea. These submarine outfalls are located in various water areas across Hong Kong.

Each year, every submarine outfall is scheduled to be tested once to ensure the integrity of the submarine outfalls for discharging effluent from the DSD sewage treatment plants. The dye test would generate a fluorescent green colour patch at the observed area, and it is the result of testing as the green dye emerges from the submarine outfall.

The dye used is a non-toxic dye and is harmless to the marine environment. The tidal current will disperse it rapidly.


 

Schedule of Dye Test Inspection of Submarine Outfalls

Position

Location

Date of test

Expected time of  observation of dye at outfall point

1

North Point PTW

15-Jun-2026

15:10 - 15:15

2

Central PTW

15-Jun-2026

15:15 - 15:20

3

Wan Chai East PTW

15-Jun-2026

15:20 - 15:30

4

Stonecutters Island STW

16-Jun-2026

14:00 - 14:15

5

Sandy Bay PTW

16-Jun-2026

15:25 - 15:35

6

Wah Fu PTW

17-Jun-2026

14:15 - 14:25

7

Aberdeen PTW

17-Jun-2026

15:15 - 15:25

 

Outfalls Location 15-17 June 2026 Schedule

 

 

 

   

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