Legionnaires' disease - Preventing Legionnaires' disease

The best way to prevent an outbreak of Legionnaires’ disease is to ensure any water system under your control is properly maintained and conforms to relevant health and safety regulations.

The two most important factors for preventing an outbreak of Legionnaires' disease are:

• temperature – any water in the system should either be cooled to below 20ºC (68ºF) or heated to above 60ºC (140ºF)
• hygiene – the water should be kept free of any impurities and never allowed to stagnate (lose its freshness from not moving)

If you are an employer or a private landlord, you have a legal duty to ensure all water systems in your premises are properly operated and maintained to prevent Legionnaires' disease or any other type of water-borne infection.

If you are a homeowner, you are responsible for the water systems in your house. In theory, these could also cause an outbreak of Legionnaires’ disease if they are not properly maintained. However, in practice, the risk is low if you keep your hot water at a high enough temperature and regularly use your water systems (to prevent stagnation).

The Health and Safety Executive (HSE) is an independent regulator for reducing work-related death and serious injury in Britain. It provides guidance about Legionnaires' disease on its website.

This includes The control of legionella bacteria in water systems: approved code of practice and guidance (PDF, 1.1MB). However, this guidance is primarily aimed at employers and explains how to carry out a risk assessment of a water system and how to manage any risks – for example, by fitting a cover to a water storage tank. 

Travelling abroad

If you are travelling abroad, be aware of the risk of Legionnaires’ disease, and seek medical advice if you develop any symptoms of Legionnaires' disease.

There is currently no vaccine that offers protection against Legionnaires' disease.

At-risk groups

If you are at increased risk of developing severe Legionnaires’ disease – for example, because you have a weakened immune system, you may want to consider avoiding water systems that could be contaminated, such as spas.