Conventional showers are promoted with health lifestyle images that do not convey important health warnings - when underused a reasonably foreseeable potential risk to health exists from legionella bacteria proliferation and exposure.

It is well documented that showers provide ideal conditions for legionella growth and exposure:

• Showers when not in use hold stagnant water in pipework kept at room temperatures suitable for bacteria growth.
• Plentiful supply of nutrients found in materials and biofilms (slimes) lining pipework and fittings.
• When showers are underused, legionella has been shown to proliferate to harmful levels in only a few days.
• When an underused shower is next used people are exposed to legionella carried by the fines sprays (mists) delivered by showerheads.

Simply assuming regular use of showers to control legionella is often described as gambling with the health of those that use them. It is widely expected that showers are most likely to fall out of use due to foreseen or unforeseen circumstances and therefore it would be prudent to plan for this as many organisations do. However, regular flushing showers as a control method has been shown to be difficult and costly to implement and subsequent lapses have occurred, resulting in infections and fatalities from Legionnaires’ disease. Safepurge showers improves safety by avoiding flushing lapses and safely purges the unwanted stagnant water to drain and immediately before use.

Legionella is a water borne bacteria, which is sausage-shaped and usually has a thin flagellum (tail like appendage) that gives it mobility in an aquatic environment. The bacteria can multiply in water in temperatures between 20°C - 45°C. As the temperature rises above 60°C the majority of bacteria will be killed within five minutes. Maintaining water temperatures above 50°C and below 20°C is therefore the main method of controlling legionella in domestic water systems as recommended by Health & Safety Authorities.

The greater the number of legionella present in water systems the more likelihood there is of contracting infections. This is why all the available guidance stresses the importance of maintaining controls to reduce legionella levels in water systems.

Legionella can enter a buildings water supply at any time, it is therefore prudent to assume legionella are present even when none are detected.

An independent survey carried out in England and Wales found legionella present in -

• 75% of business premises
• 70% of hospitals
• More than 50% of hotels

Source
Legionella live in the natural environment and water supplies, normally in low concentrations and little can be done to prevent bacteria entering building water systems at any time.

Amplification
Factors that induce the growth of legionella in water systems:

• Water temperatures between 20°C - 45°C
• Stagnant water (as found in underused shower pipework).
• The presence of iron, organic material, rubber type materials, linseed oil based jointing compounds etc.
• The presence of complex biofilms lining the internal aspects of showers and pipework, providing an ideal habitat for legionella to grow (see image of biofilm at top of page).
• Time, the longer water remains stagnant this will increase the legionella multiplication period. When showers are underused, legionella has been shown to proliferate in the stagnant water to harmful levels in only a few days.

Dissemination
When underused showers are next used, contaminated stagnant water is delivered in sprays and fine mists are produced, which carry the legionella bacteria. When inhaled infections may result.

However, removing the contaminated stagnant water safely away from and avoiding contact with people, will significantly reduce the risks to health - this is the advocated design function of Safepurge showers.

Susceptibility

• Legionnaires’ disease can strike the elderly, healthy and infirm alike. It is important to recognise highly susceptible occupants, such as those in hospitals, nursing homes, hotels and cruise ships, particularly those attracting the elderly.
• Pontiac fever is another legionella infection, characterised by severe flu-like symptoms. The majority of people are at risk, including children and professional athletes.

Due to difficulties and costs involved in diagnosing Legionnaires’ disease (LD), the number of reported cases grossly underestimates the scale of the problem. Prospective clinical studies indicate LD accounts for up to 5% of the 180,000 community-acquired pneumonias diagnosed in England and Wales each year. Infections may be fatal in up to 15% of reported cases. Higher infection and fatality rates can be expected amongst the susceptible, e.g. immunosuppressed patients, those suffering from a pre-existing disease and the elderly.

The incubation period is between 2-10 days. Not everyone exposed will develop LD symptoms as some may present a flu-like infection - Pontiac fever. It is important to recognise those groups of people who are at increased risk from infection, which includes, amongst others:

• People over 45 years old, especially males
• Smokers
• Alcoholics
• Diabetics
• Cancer patients

Regulations and Guidance
Always seek independent professional advice regarding health and safety responsibilities for others and always check the latest publications for different countries. In the UK there is the Approved Code of Practice & Guidance for controlling legionella in water systems (Legionnaires’ disease). It is aimed at duty holders, including employers, those in control of premises and those with health and safety responsibilities, to help them comply with their legal duty. These include identifying and assessing sources of risk, preparing a scheme to prevent or control risk, implementing, managing and monitoring precautions, keeping records of precautions and appointing a manager to be responsible for others.

Approved Code of Practice (UK)
This Code gives practical advice on how to comply with the law. If you follow the advice you will be doing enough to comply with the law in respect of those specific matters on which the Code gives advice. You may use alternative methods to those set out in the Code in order to comply with the law. However, the Code has a special legal status. If you are prosecuted for breach of Health and Safety law, and it is proved that you did not follow the relevant provisions of the Code, you will need to show that you have complied with the law in some other way or a Court will find you at fault. The Code also describes the responsibilities of designers, manufacturers, importers, suppliers and installers.

Guidance (UK)
Following the guidance is not compulsory, unless specifically stated, and you are free to take other action. But if you do follow the guidance you will normally be doing enough to comply with the law. Health and safety inspectors seek to secure compliance with the law and may refer to this guidance.