Legionella is the name given to a group of bacteria that’s found in almost all water sources including streams, rivers and lakes. It can also be found in soil, compost and mains water, and it can sometimes enter domestic water systems. Is legionella harmful? Low concentrations of the bacteria are generally not harmful. It’s only dangerous if the conditions are right for it to grow and if you inhale water droplets from a contaminated water system. The bacteria can cause a number of infections, most of which are not serious. This includes legionnaires’ disease which can be fatal in 10% to 12% of cases. What is ISHA doing? We’ve employed a water hygiene company to check whether legionella is present in any of the water systems in our homes. Where necessary, and in line with legal obligations, we’ll regularly monitor and inspect buildings to make sure water systems are clean and the water is safe to use What you can do The likelihood of legionella being in your home is very low as most households do not store huge amounts of water. they also use water regularly so it’s not standing still in pipes. Tips to make sure the water in your home is safe Setting the right temperature Legionella bacteria is more likely to grow between 20C and 45C, so where possible set hot water cylinders at 60C or above. Regular use of cold water should also ensure temperatures stay below 20C. De-scale taps and showers Legionella bacteria can grow and multiply on scale or rust. So de-scale taps and showers every three months or when there is an obvious build-up of scale. The harder the water in your area, the more frequently you should de-scale. Clean the taps in your bath, basin, and sink by brushing the scale off with a nylon brush or wiping them with a diluted bleach solution. You can also use any de-scaling solution that you can buy from hardware shops. If you have a shower that has a flexible hose, fit it with a “hose retaining ring”. This will stop it falling into bath water and so decrease the risk of contamination. Use water taps once a week This helps to make sure you don’t have water standing still in pipes. If you’ve been away for more than a week, you should run all your taps for a few minutes before using the water. You’ll also need to run the water in the shower. Make sure you remove the shower head before doing this so the water doesn’t spray and create water droplets. If you can’t remove the shower head, cover it with a towel or a plastic bag while you run the water. Flush away those bacteria The water in your home is more likely to have legionella if you haven’t used it for a while. So if you have been away for more than a week, you should: heat up your water system to the normal temperature run every tap for at least five minutes slowly flush the cold taps until the water runs cold. Remember that when flushing taps or other outlets open slowly so you don’t splash water or release droplets in the air. More information You can find more information about legionella and legionnaire's disease on the Health and Safety Executive (HSE) website. Return to Graphics Version