Legionella risk assessment · Thailand
UK-standard risk assessment and water safety plans, adapted for tropical water systems. For hotels, hospitals and commercial buildings, from Bangkok.
Reports within five working days of the survey.
Targets: Thai Department of Health (BEH) guideline, c. 2007.
Fig. 1 · A typical hotel water system and its five control points.
The other half
Most buildings in Thailand manage Legionella the same way: a contractor takes samples twice a year, the engineer drops chlorine tablets in the tank, and a certificate goes on the wall.
Every one of those things is useful. None of them tells you where the bacteria will grow next, or proves to an auditor that you are in control.
We complement the 3C Clean Hotel and GREEN Health Hotel programmes and your contractor's sampling. We do not replace them.
229 cases of Legionnaires' disease were linked to stays in Thailand between 2013 and September 2024. 97% were foreign visitors; the UK was the largest source.
Source: Division of Epidemiology, 2025
28% of the 50 hotels the Department of Health sampled in 2025 had Legionella in their water. Six months and a training round later, a third of those were still positive.
Source: Department of Health, 2026
44 accommodation visits in Thailand were triggered by the European surveillance network in 2023, joint second among all non-EU destinations. Each one starts with a sick guest and a phone call to the hotel.
Source: ECDC, 2023
Time on site depends on the size of the property. Every water system surveyed and drawn, temperatures and chlorine measured at the points that matter, each risk scored, and a report that says exactly what to fix first. Carried out to the BS 8580-1 and HSG274 method used in the UK, mapped to the checks your auditors make.
The plan that keeps the assessment alive: control limits, daily and weekly checks, logbooks your engineers will actually fill in, training for the responsible person, and review visits. Includes the procedure for closing wings in low season and bringing them back safely.
Sectors and countries
Thailand first; Vietnam, Malaysia, Singapore, Indonesia and the rest of Southeast Asia on request.
Tour-operator audits, brand standards, seasonal closures and the guest who falls ill after checking out.
Immunocompromised patients, long pipe runs, warm water everywhere. Water safety plans for accreditation.
Registers, written schemes and checks for cooling towers and the water systems around them.
Process cooling, evaporative condensers and welfare facilities on one site, assessed together.
Roof tanks, stagnant units and shared hot water. A plan juristic persons and managers can run.
Four frameworks
There is no single Legionella law in Thailand, so each property is judged by whoever audits it.
We map the assessment to the framework that applies to you and say so on the cover.
| Framework | Who asks for it | What it expects |
|---|---|---|
| Thai Department of Health guideline; GREEN Health Hotel; 3C Clean Hotel | Provincial health offices, Regional Medical Sciences Centers, Thai-owned hotels | Water management plan, responsible officer, hot water generated above 60 °C and above 50 °C at the tap, free chlorine of at least 0.2 mg/L checked daily, six-monthly sampling, records |
| ABTA guide, European 15-point plan, ECDC accommodation checklist | TUI and other European tour operators and their auditors | Documented prevention plan, trained responsible person, testing records, seasonal clean and disinfection, flushing of unoccupied rooms, spa-pool records |
| ASHRAE 188 water management programme; WHO water safety plan | International hotel brands, hospitals seeking accreditation | Programme team, system inventory and flow diagrams, hazard analysis, control measures, monitoring, verification, documentation |
| BS 8580-1 and HSG274 | UK operators, insurers and claimant solicitors | Competent risk assessment, written scheme, control limits (60 °C stored, 50 °C at outlets, cold below 20 °C), action levels and record keeping |
Assessments follow the BS 8580-1 / HSG274 method, WHO Water Safety Plan principles and the ECDC/EWGLI guidance used by European tour operators.
After a March 2025 investigation at a Phuket hotel, the Department of Disease Control recommended that sampling be done by someone other than the maintenance contractor. That is the role we fill.
Four steps
On site with your chief engineer, for as long as the size of the property needs. Every tank, heater, loop, tower, spa and little-used outlet, with temperatures and chlorine measured where the risk sits.
Schematics, a scored risk register and an action plan ranked by urgency and cost. Delivered within five working days.
Control limits, check frequencies and logbooks for your team, and a half-day session for the person who will be responsible.
Quarterly or six-monthly visits, independent sampling at TEST TECH (ISO 11731:2017), IMC Thai (AS 3896:2017) or a Department of Medical Sciences Regional Medical Sciences Center (CDC-based method), and a re-assessment after refurbishment, closure or an incident.
The assessor
Envirisk Asia is the Southeast Asian arm of Envirisk, a UK water hygiene company and Legionella Control Association member. Ken carried out and reviewed Legionella risk assessments across the UK for ten years before moving to Bangkok. He does the surveys himself.
Envirisk Asia is a trading name of KLM Hospitality Group Co., Ltd., registered in Thailand.
Next step
Tell us the property type, where it is, how many rooms and whether it has cooling towers. We reply with a price and the earliest survey date.
