Valongo Shut Two Changing Rooms After Legionella Turned Up in a Routine Water Test, and What the Law Calls a Cluster Is Something Else Entirely

The Câmara Municipal de Valongo (Valongo Town Council) confirmed on Tuesday that Legionella had been found in the water at two of its buildings: the men's referees' changing room at the Estádio de Sobrado, and the changing rooms of the sports pavilion at the Escola D. António Ferreira Gomes, in Ermesinde. Both sets of changing rooms are shut. Everything else at both sites is open.

Nobody has been reported ill. That distinction matters more than it might look, because the word being used to describe what happened in Valongo has a precise legal meaning in Portugal, and this is not it.

What the council actually found

The two detections are not the same. At the Estádio de Sobrado, the council reported finding Legionella pneumophila: the species responsible for the large majority of human cases of Legionnaires' disease. At the school pavilion in Ermesinde, what was found was recorded as Legionella spp, meaning the genus was detected but the result was not resolved to a species. Around sixty species sit under that heading, and most of them have never been linked to a human infection.

The response at Sobrado was to close the changing room immediately and then disinfect the water lines and the showers. In the council's own words, quoted in its statement, three counter-analyses will now follow "de acordo com as orientações legais e sanitárias em vigor" (in accordance with the legal and health guidance in force), and after three negative results the changing room "poderá abrir sem restrições" (may open without restrictions).

Ermesinde is further along. The same cleaning and safety procedures were applied there, the first two counter-analyses have already come back negative, and a third and final test was due this week. If it is also negative, the pavilion changing rooms reopen.

The council added a detail worth holding on to: it runs quarterly analyses on every building covered by its monitoring plan, which includes the municipality's sports and school facilities and its logistics centre, and it disinfects the hot water lines at those same sites on a regular cycle. In other words, this was not found because somebody fell ill. It was found because somebody was looking. That is not always how these things surface: the detection at AIMA's headquarters in March, which left around 300 staff potentially exposed, came to light very differently.

Why "cluster" is the wrong word here

Portuguese coverage has described the Valongo findings as two focos, which translates loosely as clusters or outbreaks. Under the law that governs this exact situation, it is neither.

Lei n.º 52/2018, de 20 de agosto (Law 52/2018, of 20 August), which established Portugal's regime for preventing and controlling Legionnaires' disease, defines both terms in article 10, and both definitions are about people rather than water. A cluster is two or more cases meeting the clinical criteria for Legionnaires' disease that initially appear linked in space, by area of residence or work, and are close enough together in their onset dates to justify further investigation. A surto, an outbreak, is two or more clinical cases closely linked in both time and place, where a common source is suspected or evidenced.

What Valongo has is an environmental detection: the bacterium in a water system, found by a scheduled test, with no reported illness attached to it. The legal machinery that switches on for a cluster or an outbreak, which under article 10 means a full environmental investigation run by the local health authority, a preliminary report within two weeks of the first cases being notified, and a final report within thirty days of the investigation closing, has not been triggered. What has been triggered is the far more ordinary business of a building owner acting on its own test results.

Who has to test, and who does not

This is the part that tends to surprise people, and it is worth knowing which side of the line your own building sits on.

Lei 52/2018 applies across every sector of activity, and article 2 sets out what it covers: heat transfer equipment attached to heating, ventilation and air conditioning systems that can generate water aerosols (cooling towers, evaporative condensers, industrial process water cooling, cogeneration cooling, humidifiers); systems in publicly accessible spaces that use water for therapeutic or recreational purposes and can generate aerosols; building water networks, specifically including domestic hot water; and irrigation or spray cooling systems, ornamental fountains and other aerosol generators running between 20°C and 45°C.

An aerosol, for the law's purposes, means suspended particles under 10 micrometres originating in water droplets. That is the whole mechanism of the disease: Legionella is not a drinking water problem, it is a breathing problem. You get it by inhaling contaminated mist, which is why showers, spa pools, cooling towers and fountains keep appearing in these stories and why kitchen taps generally do not.

The exclusions in article 2(3) are as revealing as the inclusions. Building water networks and aerosol generators are outside the regime where they sit in buildings that are exclusively or predominantly residential (defined as at least 50 percent of total floor area given over to housing), in buildings that are exclusively or predominantly offices on the same 50 percent test, or in buildings and spaces that are not open to public access and use. There are carve-outs from the carve-outs, for common areas of shopping complexes and large retail units, and for retail units with a sales area of 2,000 m² or more.

So a school sports pavilion and a municipal stadium are squarely inside the regime. A block of flats is outside it, and so is a typical office building. Note the sting in article 2(4), though: those exclusions do not apply to article 10. If a genuine cluster or outbreak is traced back to a residential building, the health authority's investigation powers reach it anyway.

What the owner has to do

Article 3 splits the duties. Owners of cooling towers and the other listed equipment carry the heaviest load: registration on a national platform within 30 days of the equipment starting up, a written prevention and control plan, audits every three years by a body accredited by the Instituto Português de Acreditação (Portuguese Accreditation Institute), and a defined procedure when results come back bad. Operators of therapeutic and recreational water systems need the plan and the risk procedure. Owners of ordinary building water networks and aerosol generators, the category Valongo's changing rooms fall into, must draw up and apply a maintenance and cleaning programme and keep an up to date record of what they have done.

The plan itself, set out in article 6, has to be built on a risk assessment that takes in the age and type of the equipment, its physical layout, the nature of the activity and how heavily the space is used, whether the system runs continuously or seasonally, and the susceptibility of the people using it, by age, health and gender. It must contain a monitoring and treatment programme specifying which parameters get analysed, where samples are taken and how often. Laboratory testing has to go to an accredited laboratory. All of it has to be kept for at least five years.

Hiring an outside contractor does not transfer any of this. Article 4(3) says so explicitly: buying in the plan, or parts of the work, does not release the person who controls the system from the obligations.

The 48-hour rule

Where a result crosses into the high risk band, article 9 gives the person responsible 48 hours from detection to report the analytical results and the measures taken to the local health authority, on a form set out in Portaria n.º 25/2021, de 29 de janeiro (Ministerial Order 25/2021, of 29 January), with the laboratory report attached.

That Portaria is where the actual numbers live. It classifies risk against Legionella concentration thresholds and prescribes minimum measures, and it does so in five separate tables, because what counts as an action level depends entirely on what kind of system you are looking at and who uses it. Part A covers cooling towers and similar equipment in buildings used by people with high susceptibility to the disease, including healthcare settings; part B covers the same equipment elsewhere; part C covers therapeutic and recreational water; part D covers building water networks including domestic hot water; part E covers irrigation, spray cooling and ornamental fountains. A reading that would force one system offline is a routine result in another.

Enforcement, and what it costs to get this wrong

Five separate bodies police this regime under article 16, and which one turns up depends on where the equipment is and what the premises do: the Autoridade de Segurança Alimentar e Económica (Food and Economic Safety Authority), the Autoridade para as Condições do Trabalho (Working Conditions Authority), the Entidade Reguladora da Saúde (Health Regulator), the Inspeção-Geral da Agricultura, do Mar, do Ambiente e do Ordenamento do Território (Inspectorate-General for Agriculture, the Sea, the Environment and Spatial Planning), and the Inspeção-Geral das Atividades em Saúde (Inspectorate-General for Health Activities).

Article 18 gives whichever body is running the case the power, where it finds a danger to public health or to safety in a workplace or a publicly used facility, to suspend the activity, close the premises preventively in whole or in part, or seize and seal the equipment, for up to six months.

The fines in article 19 run from 500 to 4,000 euros for individuals and from 2,500 to 44,890 euros for companies for the serious failures: not having a plan, not running the audits, not following the risk procedure, not registering the equipment, or not doing what the health authority tells you to do in a cluster or outbreak. A second tier, from 250 to 2,000 euros for individuals and 1,500 to 20,000 for companies, catches incomplete registrations, missed registration deadlines and failure to keep the records. Negligence is punishable, with the limits halved. Directors and managers can be made subsidiarily liable under article 20 where the company cannot pay, and article 21 allows accessory sanctions on top, including suspension of licences and loss of public subsidies for up to two years.

What this means if you live here

Legionnaires' disease is a notifiable disease in Portugal, and the Direção-Geral da Saúde (Directorate-General for Health) runs the national surveillance alongside the Instituto Nacional de Saúde Doutor Ricardo Jorge (Doutor Ricardo Jorge National Health Institute), under the strategy article 11 of Lei 52/2018 requires it to maintain. Across the European Union and European Economic Area, the European Centre for Disease Prevention and Control put the overall notification rate at 3.2 cases per 100,000 population for 2023, with rates varying widely between countries and four of them, France, Germany, Italy and Spain, accounting for 72 percent of all notified cases.

The practical points are unglamorous. The bacterium likes water that sits still at lukewarm temperatures, which is why the 20°C to 45°C band appears in the law. It reaches you through mist rather than through swallowing. The people who get seriously ill are disproportionately older, smokers, and those with weakened immune systems or chronic lung conditions; healthy adults exposed to the same water often develop nothing worse than a brief flu-like illness, or nothing at all.

Your own flat is outside the regime, but the physics are the same. The standard advice after a property has stood empty, after a long holiday, or when a rarely used shower comes back into service, is to run the hot water through it for several minutes with the room ventilated and yourself out of the mist, and to keep hot water genuinely hot rather than lukewarm. Private water sources bring their own separate rulebook, which we cover in our guide to sinking a borehole. If you use a gym, a hotel spa or a municipal pool, the operator is inside the regime and is required to hold a plan, a monitoring programme and five years of records; you are entitled to ask.

And when a council does what Valongo has done, closing a facility on the strength of its own scheduled test rather than waiting for someone to be admitted to hospital, that is the system working in the direction it was designed to work. The council's line that "não está nem nunca esteve em causa a segurança" (safety was not and never was at issue) is the kind of reassurance that is easy to be sceptical about. In this instance the sequence of events supports it.