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The discovery of legionella in hotel water systems often leads to immediate closure, but a recent case in Italy highlights how difficult it can be to eradicate the bacteria once a colonisation has taken hold.
Health officials in the city of Latina have ordered a second round of urgent disinfection at a local hotel after follow-up tests revealed that a previous attempt to clear the water system had failed. The case serves as a stark reminder for UK facilities managers and building owners that a “one and done” approach to water treatment is rarely effective when dealing with complex plumbing networks.
Following an initial positive result for Legionella pneumophila, the hotel underwent a professional deep-cleaning and disinfection process designed to sanitise the pipework and storage tanks. However, subsequent laboratory analysis conducted by Arpa Lazio—the regional environmental protection agency—confirmed that traces of the bacteria remained in the system, posing a continuing risk to guests and staff.
Local government authorities have now intervened, issuing a formal order for a new sanitisation intervention. The building’s management must now demonstrate that the water system is safe before the site can return to normal operations. This repeated failure to clear the system suggests that the bacteria may be protected within biofilm or located in “dead legs” of the pipework that the initial treatment failed to reach.
Managing the persistent risk of legionella in hotel environments
For those responsible for building safety in the UK, this case illustrates the limitations of reactive chemical dosing. When legionella in hotel water systems is identified, the immediate reaction is often to shock the system with high levels of chlorine or thermal disinfection. While these methods are standard practice, they often fail to penetrate the thick layers of organic slime, or biofilm, that build up inside older or poorly maintained pipes.
In a hospitality setting, the risk profile is particularly high due to the nature of the water use. Showers, spa baths, and decorative fountains all create fine aerosols. If these aerosols contain the bacteria, they can be inhaled by guests, potentially leading to Legionnaires’ disease—a severe and sometimes fatal form of pneumonia. The fact that the Latina hotel required a second intervention suggests the initial risk assessment may have underestimated the complexity of the internal plumbing.
UK dutyholders operating under the HSE’s ACoP L8 and HSG274 guidance will recognise that a single failed test is rarely an isolated incident. It usually points to a systemic failure in the water management regime, such as inadequate temperature control or infrequent flushing of low-use outlets.
The challenge of effective system disinfection
When traces of legionella in hotel systems persist after a chemical flush, it often indicates that the disinfectant did not achieve the required contact time or concentration at every single outlet. In large buildings, ensuring that chlorinated water reaches every tap, showerhead, and TMV (Thermostatic Mixing Valve) is a significant logistical challenge.
If the second round of treatment in the Latina case fails, the owners may be forced to look at more invasive measures. This can include the physical removal of redundant pipework or the installation of permanent secondary disinfection systems, such as chlorine dioxide generators or copper-silver ionisation. These capital-heavy solutions are often the only way to manage a building that has become chronically colonised.
The situation also highlights the importance of independent verification. The hotel could not simply claim the building was clean; they were reliant on the Arpa Lazio laboratory results to prove it. For UK compliance managers, this reinforces the need for UKAS-accredited laboratory testing following any remedial works to ensure the “clearance” is genuine and not just a temporary reduction in bacterial load.
Practical implications for UK dutyholders
This incident in Italy should prompt UK hotel operators and facilities teams to review their own secondary water systems. If a building has been operating at low occupancy, the risk of stagnation increases significantly. The failure of a single disinfection attempt often results in extended periods of closure, massive loss of revenue, and potential legal action from affected parties.
Proactive management is always more cost-effective than reactive disinfection. This includes maintaining hot water above 50°C at the outlet (55°C in healthcare) and keeping cold water below 20°C. Regular descaling of showerheads and the keeping of meticulous logbooks are not just administrative tasks; they are the primary defence against the colonisation of legionella in hotel facilities.
When a positive result occurs, the focus must move beyond the immediate “flush.” A thorough review of the Water Safety Plan is required to identify why the bacteria were able to proliferate in the first place. Without addressing the root cause—be it a faulty calorifier or a hidden dead leg—any disinfection will likely offer only a short-term fix.
The hotel in Latina remains under scrutiny as the second round of sanitisation begins. The outcome will be closely watched by local health monitors, as the persistence of the bacteria suggests that more significant structural changes to the water system may yet be necessary to ensure public safety.
