A water sample can look like a simple bottle of water, but how it is taken and handled makes a big difference to whether the result can be relied on. This is a plain-English look at the journey of a sample during Legionella sampling.
Choosing where to sample
Sample points are chosen from the water system, often a mix of the storage tank, hot water return and outlets such as taps and showers, with extra attention to places where water may be warm, stagnant or little used. The best locations come from a risk assessment, which is why the two work together.
Taking the sample
- Sterile bottles are used so the container does not contaminate the sample.
- Sampling is done carefully to avoid introducing bacteria from hands, outlets or equipment.
- The location, outlet, time and water temperature are recorded.
- Where a disinfectant may be present, the sample bottle is prepared to neutralise it so the result is not distorted.
Getting it to the laboratory
Samples are kept in suitable conditions and sent promptly to an independent accredited laboratory, where they are tested for Legionella. The sooner a sample is analysed, the more reliable it is.
Reading the results
Results are reported against the guideline levels in the HPSC National Guidelines for the Control of Legionellosis in Ireland (2009). A result needs to be interpreted in the context of the whole system, not in isolation. Our guide to what to do after a positive sample explains the follow-up steps.
How often to sample
How often depends on the building and its risk assessment. See how often Legionella sampling should be done for the general picture.
Book sampling
Safer Solutions carries out Legionella sampling for businesses across Ireland. Call 086 275 9728 or email info@safersolutions.ie.