Legionellosis causes hundreds of hospitalisations in Spain each year and, in severe outbreaks, can prove fatal. The Legionella pneumophila bacterium thrives in water installations that are not properly maintained, and legal responsibility falls directly on the installation owner.
Royal Decree 487/2022 of 21 June, which updated and replaced the previous RD 865/2003, established a strengthened regulatory framework for the prevention and control of legionellosis. Its requirements are clear, detailed and mandatory. This guide covers all the obligations that businesses need to know and comply with.
Affected installations: scope of application
RD 487/2022 classifies installations into two groups according to their risk level:
Higher-risk installations
- Cooling towers and evaporative condensers.
- Domestic hot water (DHW) systems with storage and a return loop.
- Heated water systems with agitation (spas, jacuzzis, non-standard heated pools).
- Urban spray irrigation systems.
- Ornamental fountains that generate aerosols.
- Fire-fighting water systems.
- Other systems that store water and generate aerosols.
Lower-risk installations
- DHW systems without storage or without a return loop.
- Humidifiers.
- Vehicle washing facilities.
- Drip irrigation systems (no aerosol generation).
The vast majority of commercial premises, hotels, care homes, gyms, hospitals and industrial facilities with DHW storage tanks fall within the scope of application.
The Legionella Prevention and Control Plan (PPCL)
Every owner of an affected installation is obliged to have a documented Legionella Prevention and Control Plan. This is not a generic document: it must be tailored to the specific installation and contain, at minimum:
Mandatory PPCL content
- Risk assessment: identification of critical points where the bacterium could proliferate (dead legs, stagnation zones, inadequate temperatures).
- Up-to-date plans of the hydraulic installation identifying all components.
- Maintenance programme: operations, frequencies, products used and responsible person.
- Water treatment programme: type of biocide or physical method, dosage, application points.
- Sampling and testing programme: sampling points, frequency, parameters to analyse.
- Action protocol for positive results: steps to take if the bacterium is detected or parameters fall outside range.
- Document register: logbook recording all operations performed, their results and the identity of the person carrying them out.
The PPCL must be reviewed and updated at least once a year, or whenever a significant modification is made to the installation.
Owner obligations: what you must do
Installation registration
Higher-risk installations must be registered with the relevant health authority (in the Valencian Community, the Conselleria de Sanitat).
Start-up and shutdown notification
The start of operations, prolonged shutdowns (exceeding one month) and service resumption must be reported to the health authority. After a prolonged shutdown, a full disinfection is mandatory before restarting.
Qualified personnel
Maintenance and treatment operations must be carried out by personnel who have completed a specific Legionella prevention training course, in accordance with national or regional legislation.
Accredited laboratory
Legionella detection analyses must be performed by laboratories accredited by ENAC to the ISO 11731 standard for microbiological culture of the bacterium.
Mandatory action schedule
DHW systems with storage
| Action | Frequency |
|---|---|
| Temperature check at the storage tank (>= 60 C) | Daily or continuous |
| Temperature check at the most distant point of the network (>= 50 C) | Weekly |
| Temperature check of the recirculation return (>= 50 C) | Weekly |
| Flush of infrequently used terminal points | Weekly |
| Residual biocide level check | Weekly |
| Inspection of tank and accumulator condition | Quarterly |
| Tank cleaning and disinfection | Annual |
| Full distribution network cleaning and disinfection | Annual |
| Legionella laboratory analysis | Annual (minimum) |
Cooling towers and evaporative condensers
| Action | Frequency |
|---|---|
| Water physicochemical parameter check (pH, conductivity, biocide) | Three times per week |
| Visual inspection of the tower | Monthly |
| Cleaning of basin, packing and drift eliminators | Six-monthly |
| Legionella laboratory analysis | Quarterly |
| Full tower cleaning and disinfection | Annual |
| General mechanical and structural review | Annual |
Temperatures: the first line of defence
Thermal control is the fundamental pillar of prevention. Legionella multiplies in the 20 C to 45 C range and is killed at temperatures above 70 C. The regulatory values are:
| Installation point | Minimum required temperature |
|---|---|
| DHW storage tank | 60 C |
| Distribution network (most distant point) | 50 C |
| Recirculation return | 50 C |
| Point of use (tap, shower) | 50 C (before mixing) |
To prevent scalding at points of use, thermostatic mixing valves reduce the temperature to 38-42 C at the tap, while maintaining a high temperature throughout the distribution network.
Water treatment
RD 487/2022 requires at-risk installations to have a water treatment system that maintains conditions hostile to the bacterium. The most common treatments are:
Chemical treatments
- Chlorine (sodium hypochlorite): the most widely used biocide in DHW. A free chlorine residual of 0.2 to 0.8 mg/l must be maintained at terminal points.
- Chlorine dioxide: more stable than chlorine, does not generate trihalomethanes and is effective against biofilm. Increasingly used in large installations.
- Hydrogen peroxide combined with silver: a chlorine-free option, suited to installations where chlorine causes corrosion problems.
Physical treatments
- Thermal treatment (heat shock): raising the temperature of the entire network above 70 C for 30 minutes. Effective as an emergency treatment but not as the sole long-term preventive method.
- Ultraviolet radiation: effective for point-of-use disinfection but does not leave a protective residual in the network.
- Copper-silver ionisation: generates metallic ions that destroy bacteria. Effective but requires rigorous concentration monitoring to avoid toxicity.
Response to positive results
If a laboratory analysis detects Legionella in the installation, the response protocol depends on the concentration:
| Result | Required action |
|---|---|
| < 100 CFU/L | Installation under control. Maintain standard programme. |
| 100 - 1,000 CFU/L | Review the maintenance plan. Intensify monitoring. Repeat analysis in 15 days. |
| 1,000 - 10,000 CFU/L | Disinfect the installation. Review the PPCL. Notify health authority if higher-risk installation. |
| > 10,000 CFU/L | Shut down the installation. Shock disinfection. Full mechanical cleaning. Mandatory notification to health authority. |
Detection of Legionella pneumophila serogroup 1 (the most pathogenic) at any concentration must be treated with particular attention.
Penalties
Non-compliance with the obligations set out in RD 487/2022 is sanctioned under General Public Health Law 33/2011:
- Minor offences: missing records, delays in non-critical operations. Fines of up to 3,000 euros.
- Serious offences: absence of a PPCL, failure to carry out mandatory testing, non-compliance with the maintenance programme. Fines of 3,001 to 60,000 euros.
- Very serious offences: situations posing a grave risk to public health, obstruction of health inspection, repeated serious offences. Fines of 60,001 to 600,000 euros.
In the event of a legionellosis outbreak attributed to an installation, the owner may also face civil and criminal liability.
Prevention as responsible management
Complying with Legionella regulations is not a bureaucratic burden: it is a public health obligation that protects both the installation’s users and the owner from legal liability. The costs of a properly implemented prevention programme are far lower than those of a penalty, a precautionary closure or, of course, an outbreak with victims.
At Acoval, we design, install and maintain heating and DHW systems with full compliance with Legionella prevention protocols. We also provide maintenance services for hydraulic installations with an integrated Legionella control programme.
If you need to implement a prevention plan or review the condition of your DHW installation, contact us and we will advise you.
