There is no single answer for every building, but there is clear guidance. Healthcare settings, including nursing homes, should sample at least twice a year. For everyone else, your legionella risk assessment sets the frequency. This guide explains how that works and when you should test sooner.
What legionella sampling tells you
Legionella bacteria live naturally in water and multiply when conditions suit them. They grow best between 20°C and 45°C and are killed within minutes above 60°C. Your day-to-day controls, such as temperature checks and flushing, are designed to keep the bacteria from growing.
Sampling is how you check that those controls are working. A water sample is taken from your system and cultured in a laboratory. The result shows whether legionella is present and at what level.
What the Irish guidance says
The main reference is the National Guidelines for the Control of Legionellosis in Ireland, 2009, published by the Health Protection Surveillance Centre. Two of its recommendations matter most here:
- Routine water sampling should be done at least twice a year in healthcare facilities, including nursing homes and long-stay care facilities.
- The legionella risk assessment should be reviewed at least once a year, and sooner if the system changes or controls fail.
The Health and Safety Authority also asks employers to carry out a written risk assessment, record the findings and review it at regular intervals.
Nursing homes and healthcare settings
Residents in care are more likely to become seriously ill from legionella, so the standard is higher. Plan for sampling at least every six months, and keep the results with your water safety records so they are ready for inspection.
Hotels, leisure centres and accommodation
Showers, spa pools and rooms that sit empty between guests all raise the risk. Your risk assessment will set a sampling schedule based on how the building is used. Spa pools and cooling towers carry a higher risk than ordinary hot and cold water systems and need closer attention.
Offices, schools and other workplaces
Many lower-risk workplaces do not need routine sampling if temperatures are well controlled and outlets are used regularly. The risk assessment makes that call. Sampling becomes more important where the system is old or complex, or where temperatures are hard to control.
When to sample outside the normal schedule
Arrange extra sampling when:
- Temperature checks show hot water is too cool or cold water is too warm.
- A building, wing or floor reopens after being closed.
- Work has been done on the water system.
- A previous sample came back positive and you need to confirm the fix worked.
- There is a suspected or confirmed case of Legionnaires’ disease linked to the building.
What happens during a sampling visit
A trained technician takes samples from agreed points in the system, usually including the storage tank, the water heater and outlets nearest to and furthest from them. The temperature is recorded at each point. Samples go to an independent accredited laboratory. Legionella has to be grown in culture, so results are not instant, and we will tell you when to expect yours.
What to do if a result is positive
A positive result does not always mean people are in danger, but it does mean action is needed. Depending on the level, that can range from reviewing your controls and re-sampling to disinfecting the system. Your sampling provider should explain the result and the next steps clearly.
Book legionella sampling with Safer Solutions
We carry out legionella sampling and legionella risk assessments for nursing homes, hotels and businesses across Ireland, including Dublin, Cork, Limerick and Galway. Call 086 275 9728, email info@safersolutions.ie or request a quote and we will set up a schedule that suits your building.