Water temperature
Hot-water storage below 60 °C and recirculation loop temperatures below 55 °C at return points create optimal growth conditions (20–45 °C is the critical range; peak at 35–37 °C).
LEGIONELLA RISK ASSESSMENT
ITALY — COMPLETE GUIDE
A plain-English guide to Legionella risk assessment obligations in Italy: who must do it, what the DVR Legionella must contain, how sampling is conducted and how results map to the ISS national action levels.
Overview — Italian regulatory context
Under Italian law, a Legionella risk assessment is not a recommendation — it is a legal obligation for many facility types. The primary reference is the State-Regions Agreement of 7 May 2015, which requires a written risk assessment document (DVR Legionella) for hotels, nursing homes, hospitals, gyms, cooling-tower operators and other specified premises. For employers, Legislative Decree 81/2008 imposes the same obligation under biological risk legislation. Testing must be carried out by an ACCREDIA-accredited laboratory using the UNI EN ISO 11731:2017 culture method — reports from non-accredited laboratories are not accepted by Italian health authorities (ASL).
Why water systems pose a risk
Key Legionella risk factors in buildings
Understanding these factors is the first step of any risk assessment. Italian assessors evaluate each risk factor against the specific water system and facility type.
Stagnation and dead-legs
Infrequently used branch pipes, end-of-line outlets (e.g. closed guestrooms, seasonal shut-down circuits) and dead-legs trap warm water and support biofilm accumulation.
Biofilm and scale
Biofilm on pipework and storage-tank surfaces protects Legionella from disinfection. Scale, sediment and corrosion products provide nutrients and anchor biofilm communities.
Aerosol generation
Showers, spa jets, cooling towers, humidifiers and dental unit waterlines produce fine aerosol droplets (< 5 µm) that can penetrate deep into the lung.
System complexity and age
Extensive pipe networks, multiple storage tanks, recirculation loops and point-of-use mixing valves increase the number of potential colonisation zones. Older systems are at higher risk from biofilm accumulation.
Vulnerable users
Facilities serving immunocompromised, elderly or post-surgical patients face the highest clinical consequence from any colonisation event and therefore require the most stringent control levels.
Assessment methodology
Five-step risk assessment process
How a compliant Legionella risk assessment is conducted for an Italian facility, from the initial site survey to the certified laboratory report.
Technical site survey
A qualified technician visits the facility and inspects the entire water distribution system: storage tanks, boilers, pipework, recirculation loops and all aerosol-generating equipment. Risk points (dead-legs, low-use outlets, temperature deviations) are identified and mapped.
Risk assessment document (DVR Legionella)
The surveyor produces the DVR Legionella — the written risk assessment document required by the Italian State-Regions Agreement 2015 and D.Lgs. 81/2008. The DVR records the system layout, risk matrix, sampling plan and corrective-action procedures.
Environmental sampling
Water samples are collected at the identified risk points under a documented chain of custody. Sample volumes, temperatures, collection times and exact locations are recorded. Samples are transported within the required temperature and time window.
ACCREDIA-accredited laboratory analysis
Samples are analysed using the UNI EN ISO 11731:2017 culture method (BCYE selective agar, 7–10 days at 36 °C ± 1 °C) by an ACCREDIA-accredited laboratory. Results are expressed in CFU/L for each sample point.
Certified test report and action plan
The accredited laboratory issues a signed certified test report. Results are interpreted against ISS national action levels with a graded corrective-action plan. International operators receive an English-language operational summary alongside the Italian-format report required for ASL audits.
Required documentation
What the DVR Legionella must contain
The DVR Legionella (Documento di Valutazione del Rischio Legionella) is the mandatory written record of your risk assessment. Here are the six core sections required by the Italian State-Regions Agreement 2015.
System description and schematic
A complete plan of the domestic hot- and cold-water distribution system: storage tanks, boilers, recirculation loops, key outlets and any aerosol-generating equipment (cooling towers, humidifiers, spa circuits).
Risk identification
Identification of all risk points based on the physical inspection: dead-legs, low-use outlets, sections with temperature problems, biofilm-prone materials, backflow prevention gaps.
Risk assessment matrix
Qualitative or semi-quantitative risk matrix assigning a risk level (low / medium / high / very high) to each identified hazard based on likelihood and potential severity of Legionellosis.
Sampling plan
List of sampling points, sampling frequency by risk level and reference to UNI EN ISO 11731:2017 culture method. At least one full system sample per regulatory cycle is required.
Corrective action plan
Documented procedures for each action-level outcome: immediate notification, re-sampling schedule, disinfection protocol, temperature checks and root-cause corrective actions.
Monitoring register
Ongoing log of temperature readings (storage and circulation return), sampling results, corrective actions taken and dates. Must be available on-site for ASL health authority inspection.
The DVR Legionella must be kept on-site and updated whenever the water system is significantly modified or whenever sampling results trigger a corrective-action review. ASL inspectors may request it at any time.
Interpreting results
ISS national action levels
Results expressed in CFU/L (colony-forming units per litre) are compared against the Italian National Institute of Health (ISS) action levels to determine the required response.
< 100 CFU/LNo action
Results are within acceptable limits. Record in the monitoring register and continue scheduled monitoring.
100–999 CFU/LAlert
Investigate possible causes (temperature, stagnation, biofilm). Increase sampling frequency. Review maintenance logs.
1,000–9,999 CFU/LAction required
Corrective actions are mandatory: hyperchlorination or thermal shock disinfection, temperature adjustment, dead-leg elimination. Re-sample after remediation.
≥ 10,000 CFU/LImmediate action
Consider immediate closure or restriction of the implicated water system until results fall below 1,000 CFU/L. Notify the relevant health authority (ASL) in high-risk premises.
Action levels apply to results from hot-water systems analysed by ACCREDIA-accredited laboratories using UNI EN ISO 11731:2017. Cold-water systems have separate thresholds; specific higher-risk areas (e.g. ICU wards, transplant units) may require lower trigger concentrations under facility-specific protocols.
Related resources
Continue your research
Legal requirements
Full guide to the Italian regulatory framework: State-Regions Agreement 2015, D.Lgs. 81/2008, EU Directive 2020/2184 and mandatory sampling frequencies by facility type.
Read more →Testing services
ISO/IEC 17025-compliant Legionella sampling and ACCREDIA-accredited laboratory analysis across all 21 Italian regions. English compliance documentation available.
Read more →Technical glossary
Definitions for CFU/L, DVR Legionella, dead-leg, biofilm, BCYE agar, UNI EN ISO 11731:2017, action levels and 30+ further technical terms.
Read more →Commission a compliant assessment
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Frequently asked
Risk assessment FAQ
Six answers covering legal obligations, DVR Legionella requirements, sampling frequency, laboratory standards and action levels for Italian facilities.
Is a Legionella risk assessment legally mandatory in Italy?
Yes, for many facility types. The Italian State-Regions Agreement of 7 May 2015 ("Linee guida per la prevenzione e il controllo della legionellosi") makes a documented risk assessment mandatory for hotels, nursing homes, hospitals, gyms, public swimming pools and industrial facilities with cooling towers. D.Lgs. 81/2008 imposes the same obligation for all employers whose workplaces include aerosol-generating water systems. Residential condominiums with centralised hot-water systems are strongly recommended — and in practice expected — to carry out annual assessments.
What is the DVR Legionella?
DVR Legionella (Documento di Valutazione del Rischio Legionella) is the written risk assessment document required by Italian law. It must describe the water distribution system, identify all risk points, assign a risk level to each hazard, set out the sampling plan (frequencies and methods) and document the corrective-action procedures for each action-level outcome. The DVR must be kept on-site and made available to health authority inspectors (ASL). It must be updated whenever the water system is significantly modified or whenever positive results trigger a review.
How often must environmental sampling be carried out?
Frequency depends on facility type and risk level. Under the State-Regions Agreement 2015: hotels (3+ stars) require semi-annual sampling with an annual DVR update; nursing homes and care facilities require quarterly sampling (monthly in point-of-care areas); hospitals are typically monthly to quarterly depending on a facility-specific risk assessment; gyms and spas require semi-annual sampling (pool circuits monthly). Industrial facilities with cooling towers require at least quarterly sampling under D.Lgs. 81/2008.
What laboratory standard is required for Italian compliance testing?
Italian health authorities (ASL) accept only certified test reports issued by ACCREDIA-accredited laboratories using the UNI EN ISO 11731:2017 culture method. ACCREDIA is Italy's national accreditation body and a signatory of EA, IAF and ILAC mutual recognition arrangements, so accreditation is internationally recognised. Non-accredited laboratories or non-standard methods produce reports that are not valid for regulatory inspection purposes.
What action levels apply to Italian test results?
The ISS (Italian National Institute of Health) action levels are: < 100 CFU/L — no action; 100–999 CFU/L — alert, investigate causes and increase monitoring; 1,000–9,999 CFU/L — corrective actions required (disinfection, temperature adjustment, dead-leg elimination) followed by re-sampling; ≥ 10,000 CFU/L — immediate action, consider shutting down or restricting the affected water system until results fall below 1,000 CFU/L.
Can a risk assessment carried out in another EU country satisfy Italian obligations?
No. While laboratory results from ILAC MRA-signatory accredited laboratories across the EU are mutually recognised, Italian compliance requires the DVR Legionella to be produced by a qualified technician with direct knowledge of Italian law (the 2015 State-Regions Agreement and D.Lgs. 81/2008) and the facility's water system. An assessment carried out under UK, German or French law would not satisfy the format and content requirements of Italian health authority inspections.