Risk of Legionella with Showerheads

Risk of Legionella with Showerheads

By on Apr 19, 2017 in Blog |

Showering is something that most of us will do on a regular basis (unless you’re my beloved Uncle Jim). It is therefore a water source you’re exposed to on a regular basis. Legionella can be found in most water sources, however Legionnaires’ Disease can’t be contracted from drinking water. Shower heads pose a much higher risk as showers create a spray which means water droplets can be inhaled and the bacteria can enter your lungs. It’s because of this that showers are a much higher risk system and need to be managed with care.


Why does Legionella grow on shower heads?

Limescale – The limescale, sludge and rust that can build up on a shower head is the perfect breeding ground for Legionella. It gives them nutrients that help the bacteria to survive and in some cases protect them from any chlorine in the water.

Stagnation – The hose pipe attaching a shower head to the water system can hold stagnated water for potentially long periods of time if not flushed through regularly. Stagnated water helps Legionella to grow so water stagnated in the hose or in any dead legs/ends in the system are an added risk. (see here for our Legionella Glossary)

Water temperature – Temperatures between 20 and 40°C are ideal for the growth of Legionella. The hot water fed into your shower should be no less than 50°C with a mixer valve (TMV) introducing cooler water to reduce the risk of scalding. If water has to travel a long way through pipes for example in bigger complexes such as a hotel or care home, this can also lead to the water cooling down before it hits the shower and therefore gives Legionella a chance to grow.


Fortunately the risk is reasonable easy to manage. If you have concerns about your system the first thing you can do is carry out a Legionella Risk Assessment. This needs to be carried out by a competent professional who can assess the bacterial risks. We can carry out a full risk assessment for you if you need help!

If there is a risk, shower heads will need to be thoroughly cleaned and disinfected or possibly replaced (this will need to be done by a professional) and the outlets will need to be flushed on a regular basis to reduce the risk of water stagnation (this can easily be done in-house).


If you would like a risk assessment carried out or need your water systems treated you can contact us on 01789 330830 or email ellie@key-environmental.co.uk