The aerobic gram-negative bacteria of the Legionella genus can cause a disease called Legionellosis in humans, affecting lungs and potentially resulting in the death of people at risk.

Globally, more than 85% of Legionellosis is caused by a single species of the bacteria: Legionella pneumophila and, more specifically, serogroup 1.

Legionella can be found in aquatic environments. From natural springs such as thermal water, rivers, lakes, sludge, etc., it reaches artificial environments such as urban water piping systems, water systems of buildings, reservoirs, pipes, fountains and swimming pools, which can become real incubators for the pathogen.

The infection is not contracted by ingesting contaminated water but by inhaling aerosol particles containing Legionella. The danger posed by the droplets is inversely proportional to their size: the smaller the droplet is, the more it can reach the lower respiratory tract.

The law on the matter imposes procedures and limits and addresses the issue from different points: occupational safety, environmental monitoring and, more in general, the safety of all the water intended for human consumption.

The Italian Legislative Decree No 81/2008 (Italian Consolidated Law on Health and Safety at Work) requires employers to assess the Legionellosis risk in relevant places. To comply with this requirement, they must draw up a Risk Assessment Document (DVR) and adopt appropriate pre-emptive and protective measures.

The State-Regions Agreement of 2013 and 2015 (79/CSR of 07/05/2015) defines the Legionella Risk Control Protocol composed of 3 phases:

- Risk Assessment: annual or biennial depending on the criticality, with sampling usually carried out every six months (in case of any change in plant conditions and/or report of a possible case of Legionellosis, the risk analysis must be repeated)
- Risk Management: appointing a person responsible for monitoring
- Risk communication

The facilities that are subject to said obligations are:

- Tourist-accommodation facilities (hotels, holiday homes, B&B, beauty farms, holiday resorts, campsites, swimming pools, etc.)
- Health care facilities (hospitals, medical centres, dental centres, etc.)
- Thermal establishments

Each facility must keep a Maintenance Register containing ordinary and extraordinary maintenance operations on the monitored systems based on the Risk Analysis.

In addition, the European Directive EU 2020/2184 has recently updated the quality standard for drinking water establishing that the presence of Legionella must be lower than 1000 CFU/l. This limit was transposed into Italian law with Legislative Decree No 18 of 23 February 2023 indicating Legionella as one of the ‘relevant parameters for risk assessment and management of internal distribution systems’.

Qualitative and quantitative microbiological testing of Legionella in water is carried out in compliance with applicable Italian and European guidelines and regulations.

All water testing services are also available for the maritime industry: Onboard water intended for human consumption and bottled water (Decree No 123 of 28 January 2020).