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Since 2011, EMSD has been able to enter premises and sample fresh water cooling towers at random. A result between 10 and 1,000 cfu/mL of Legionella draws an advisory letter; 1,000 cfu/mL or above draws a statutory nuisance notice, and failing to comply with it is an offence. In the most recent published round — January to June 2026 — roughly one sample in ten showed detectable Legionella above the Code's threshold. The table below tracks the published rounds and their sources.
These are the sampling announcements EMSD and the HKSAR Government have published, as cited on this site. Each row links to its source.
| Period | Samples | Buildings | 10–1,000 cfu/mL (advisory letters) | ≥1,000 cfu/mL (nuisance notices) | Source |
|---|---|---|---|---|---|
| December 2024 sampling round | 89 | 68 | Not stated in the announcement | 1 sample at or above the threshold | Government announcement, 8 Jan 2025 |
| January–June 2026 routine surveillance | 348 | 219 | 35 samples | 1 sample | EMSD sampling statistics (retrieved 15 Jul 2026) |
This table is updated when EMSD publishes new sampling announcements. Figures are the government's own published numbers; check the linked sources for the current data.
Three things stand out for anyone responsible for a building:
The realistic risk for most buildings is not prosecution. It is being the one in ten — the building whose sample lands in the advisory band because the treatment programme drifted between visits. The difference between the buildings in that group and the ones outside it is not luck; it is whether someone is actually running the programme: continuous treatment, quarterly testing, cleaning at least every 6 months, and a dated record of all of it, kept for at least 2 years.
If EMSD sampled your tower tomorrow, would you know what the result would be? A working programme means the answer is yes — because your own test results already tell you. If the honest answer is no, that is the gap to close, and it is closable in one visit.
For the full rulebook — the thresholds, the action ladder and the record rules — see the EMSD Code of Practice explained. For what an owner is responsible for, see Legionella and cooling tower compliance. If a result has already come back high, or a notice has arrived, go straight to emergency Legionella and EMSD notice response; the printable checklist covers the routine duties that keep a tower out of both bands.
Yes. Since 2011 EMSD has been able to enter premises and sample fresh water cooling towers at random — these are surveillance visits and you do not get notice. The results are published: in the January–June 2026 round EMSD took 348 samples across 219 buildings, and two published rounds eighteen months apart both found towers over the threshold.
A result between 10 and 1,000 cfu/mL draws an advisory letter putting the problem on record. A result at or above 1,000 cfu/mL draws a statutory nuisance notice requiring emergency decontamination and re-testing — failing to comply is an offence, and EMSD publishes the building locations issued with nuisance notices.
In the most recent published round — January to June 2026 — 35 of 348 routine surveillance samples sat in the 10–1,000 cfu/mL advisory band, roughly one in ten, and 1 sample reached the 1,000 cfu/mL statutory trigger. In the December 2024 round, 1 of 89 samples was at or above that threshold.
We will test your water against the Code's criteria and tell you plainly where you stand.