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EnviroMail 063 HK - Updated requirements for commissioning of fresh water plumbing system
In late June 2022, Water Supplies Department (WSD) updated the requirements for the commissioning of
fresh water plumbing system
In late June 2022, Water Supplies Department (WSD) updated the requirements for the commissioning of fresh water plumbing system under the WSD Circular Letter No. 5/2022, the modifications are based on the previous Circular Letters No 9/2017 (new plumbing works) and No. 10/2017 (plumbing works in occupied buildings/village houses), which apply to the works covered by Form WWO 46 Part IV submitted on or after 30 June 2022.
Changes in acceptance criteria
The main changes in WSD Circular Letter No. 5/2022 is the update in the acceptance criteria of pH at 25oC, free chlorine and conductivity at 25oC, below is the summary table with the differences being bolded and compared between the new Circular Letter No. 5/2022 and the previous versions:
| Parameter; | Acceptance criteria | |
| WSD Circular Letter No. 5/2022(NEW) | WSD Circular Letter No. 9/2017 and 10/2017 | |
| Chemical and physical | ||
| Turbidity | ≤ 3.0 NTU | ≤ 3.0 NTU |
| Colour | ≤ 5 Hazen Unit (Colour Unit) | ≤ 5 Hazen Unit (Colour Unit) |
| pH at 25oC | ≥ 6.5 and ≤ 9.5 | ≥ 6.5 and ≤ 9.2 |
| Free Chlorine | ≤ 1.5 mg/L | ≥ 0 and ≤ 1.5 mg/L |
| Conductivity at 25oC | ≤ 500 µS/cm | ≤ 300 µS/cm |
| Metals | ||
| Lead | ≤ 10 µg/L | ≤ 10 µg/L |
| Chromium | ≤ 50 µg/L | ≤ 50 µg/L |
| Nickel | ≤ 70 µg/L | ≤ 70 µg/L |
| Cadmium | ≤ 3 µg/L | ≤ 3 µg/L |
| Copper | ≤ 2000 µg/L | ≤ 2000 µg/L |
| Antimony | ≤ 20 µg/L | ≤ 20 µg/L |
| Bacteriologial | ||
| Heterotrophic Plate Count (HPC) | ≤ 20 cfu/mL | ≤ 20 cfu/mL |
| E. coli | 0 cfu/100mL | 0 cfu/100mL |
Reference
www.wsd.gov.hk/filemanager/article/en/upload/524/Final%20CL%205_2022_Eng_full.pdf
Sampling procedure for new plumbing works and occupied buildings
For the sampling procedure, WSD Circular Letter No. 5/2022 for new plumbing works/unoccupied buildings and occupied buildings/village houses is the same as WSD Circular Letter No. 9/2017 and 10/2017. Below is the sampling sequence under 2 different building types:Reporting and HOKLAS accreditation
ALS HK has HOKLAS accredited all testing parameters and committed to follow the requirements from WSD on sampling and reporting, such as having competent person with proper training to conduct the sampling, provide photo records and checklist in the test reports for submitting to WSD.The report turnaround time for testing fresh water plumbing system is as follows:
| Type of service | Turnaround time | Remark |
| Regular service | 6 calendar days | Without public holidays in between |
| Express service | 4 calendar days | Applicable to sampling on Monday or Tuesday, without public holidays in between |
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