Mountain huts : Attention to Legionella

With this article we cater mainly Lee managers mountain or to persons who are responsible for the hygiene of these structures in order to prevent the problem related to legionella; also of course we hope to provide information to all users of mountain huts in order to take the necessary precautions to prevent the contraction of this disease.


Last year the CAI He was involved in a rare problem, but important medico-legal point of view, on the topic of "health in shelters". The case concerned the death of a Mountaineer Spanish, died at a hospital in Aosta following a severe pneumonia caused by an infection by 'Legionella’. In General, the problem of a possible infection by 'Legionella' in a mountain refuge should be taken into consideration and evaluated not only in Italy but in all countries.

In Europe and in Italy there are specific guidelines for tourist accommodation facilities (What are the shelters Alpini) for the prevention of this infection. Di conseguenza la Commissione Medica del CAI ha elaborato e proposto dei suggerimenti molto semplici per la prevenzione di questo problema. Similarly the UIAA MedCom has adapted these simple and practical rules, making them easily applicable and valid for all mountain structures in the world.


The term "Legionnaire's disease " or Legionellosis refers to infections caused by Legionella pneumophila and other similar bacteria. Questi batteri sono infettanti solo per via respiratoria e generalmente in individui suscettibili nei quali l’inalazione dei batteri mediante l’aerosol o goccioline di acqua (shower) can cause severe pneumonia, in extreme cases to fatal.

The Legionella are bacteria are widespread and are found in many aquatic environments where they feed on algae and organic substances present in sewage sludge and sediments, with a pH of 5 and 8. They tolerate a wide range of temperatures, Although under the 20° and over 50° bacteria are inactive and over 60° do not survive.

When bacteria penetrate plumbing systems built by man, they can proliferate in special favourable circumstances. If you create water droplets that are released into the environment, people invested are at risk of inhaling the bacteria. To eliminate and reduce this risk, control measures must be put in place to prevent the proliferation of these microorganisms in the water system and to minimize the production of water droplets and aerosols.

The European border surveillance Program EWGLI (European Working Group for Legionella Infections) started in 1986 and is coordinated by the 1993 the National Laboratory of Bacteriology Stockholm and from the Public Health Laboratory Service (PHLS), Communicable Disease Surveillance Centre (CDSC) of London. The program allows for the interchange of information between the countries of Europe on epidemiology and for appropriate interventions.

Recommendations for mountain huts

The following are practical tips for preventing infections from Legionella in mountain huts, redatti tenendo ben presente le difficoltà che esistono in questo tipo di strutture ma facendo anche riferimento alle linee-guida internazionali esistenti (adapted from EWGLI).

1) Se l’acqua sanitaria viene scaldata at the time of its use (gas boiler), then the problem does not arise because the bacteria do not proliferate in cold water.


2) Se l’acqua sanitaria calda è already present because heated by electric boiler, solar panels, etc., and then "stagnate" in containers, then you will need the following measures:


  1. Action on water container:

Once a year, seasonal reopening, pulire e disinfettare il contenitore con cloro alla concentrazione di 50mg/l per 2-4 hours.


  1. Action on water:

Once a year, seasonal reopening, disinfect the water supply system by using:


  1. The. Thermal shock treatment at 70-80° C for relatively short periods is used for both the emergency ' and ' periodic disinfections, as part of a long-term monitoring programme. Thermal disinfection takes place by increasing the temperature of the entire water system domestic hot water distribution to 70-80° C, then circulating this water throughout the system for 3 days. To be effective, the hot water temperature shall be such as to ensure that the taps it does not drop below 65° C. From every tap water should run continuously at this temperature for at least 5 minutes (necessary measure).

In practice: periodically, during the opening season, the water is heated to 70-80° C to 30 min. per day, for three consecutive days.




  1. II. Ongoing maintenance of temperature between 55-60° C: At 60° C it takes about 2 minuti per inattivare il 90% della popolazione della L. pneumophila. La validità di mantenere una temperatura circolante a 60ºC è stata dimostrata sia in strutture ospedaliere sia in quelle alberghiere. Hot water systems maintained at temperatures above 50° C are less frequently colonized by Legionella. The circulating water at 60° C so that the temperatures at each tap is at least 50° C (best 55° C) per la durata di un minuto di apertura del rubinetto è il metodo più comunemente usato per controllare la Legionella hot water distribution systems.

In practice: l’acqua è All the time maintained at room temperature > at 60° C.




  1. III. Hyper-chlorinationshock: Even the chlorine has been used for the treatment of hot water systems. Poiché l’azione battericida del cloro è pH–dipendente e si reduce rapidamente a valori superiori a 7, il pH dell’acqua deve essere monitorato frequentemente ed eventualmente corretto.

Questo metodo si attua in acqua a temperatura inferior a 30°C, by adding a single dose of chlorine free chlorine concentrations until by 20-50 mg/l throughout the water system, including the most distant points.

After a period of at least 2 hours at a chlorine concentration of 20 mg/l or at least 1 now at a concentration of 50 mg/l, the water is removed and replaced with fresh water in the pipes up to regain a chlorine concentration of 0.5-1 mg/l.

In practice: periodically water chlorine concentration is maintained at 50 mg/l for 1 now or 20 mg/l for 2 hours.




  1. IV. Chlorination continues: This method is accomplished by adding constantly of chlorine in the water, generally in the form of calcium hypochlorite or sodium hypochlorite. Chlorine residual levels may vary depending on the quality of water, of flow and amount of biofilm in the system. In any case the residual disinfectant level must be between 1 and 2 mg/l. If there are areas where water stagnates or where there are traffic problems, in those areas the chlorine will not be able to inactivate the Legionella.

In practice: Aggiungere IPOCLORITO di SODIO nell’acqua, to obtain a final concentration of 1-2 mg/l.


In the two latter cases, è necessario esporre opportuni cartelli di avviso a tutti i rubinetti che indichino chiaramente: "hot water chlorinated, not suitable for drinking "



  1. Action on water dispensers (faucets, shower dispensers):

Keep the showers and faucets clean and free of limescale.

Once a year, seasonal reopening, clean the taps and dispensers with a decalcifier (e.g. acetic acid or vinegar!), then disinfect them and leave them to soak for one night in a sodium hypochlorite solution (bleach!), Finally rinse before re-installation.

In guest services, slide the water through all taps and showers for a few minutes at least once a week if they are unused and always before each use.


Source : Official rules of the Medical Committee UIAA

of team 29 July 2011