Legionella flushing of little used taps and showers

Legionella flushing of little used taps and showers

One key point to note is that legionella bacteria will multiply far more readily in stagnant water, i.e. water that is not moving. This is where flushing comes in. There may be parts of the water system that are not regularly used. For example, in a school during the holidays, there could be rooms that are often empty. In this situation, a plan should be put in place to ensure these little-used taps, showers, other water outlets, and sections of the water system are thoroughly flushed through on a regular basis. This should be done at least once a week (minimum of five minutes) to ensure that stagnant water conditions are avoided and to minimise the possible build-up of bacteria.

Legionella testing pre and post flush

Another point worth being aware of is the need to properly label all legionella water samples you take from any point of the water system you are responsible for. If legionella is present in the system (which it is more than likely to be, even at very low and manageable levels), it will often show at different concentrations depending on whether the sample was taken before (pre-flush) or after flushing (post-flush). So, whenever you take a sample, be sure it is labelled as such, so you know when it was taken and from where. Of course, the testing of water samples for legionella bacteria may not always be required; it will depend on the results of the risk assessment for each individual water system and a number of other site-specific risk factors that are outlined by the Health & Safety Executive in their legionella code of practice and guidance documents.

The benefits of regular flushing

Regular flushing of water outlets is therefore an important part of managing the legionella bacteria within a water system and helping to keep it at safe levels. It may not always be needed, but when it is, it could make the difference between managing the bacteria levels or allowing them to multiply out of control and increasing the risk levels.