KEEP BATHROOMS SAFE AND COMPLIANT

Legionella risks can be mitigated through good design and proactive management, says Gary Nicholls, Managing Director of Swiftclean.

Of course — here’s a cleaner, more polished rewrite that keeps the same structure and technical detail while improving flow and readability.

Legionella prevention starts with good bathroom design

Summer is the peak season for Legionella growth, with cases of Legionnaires’ disease typically rising between July and October. However, while the warmer months provide a useful reminder to review water hygiene measures, the risk of Legionella is present throughout the year.

In March 2026, for example, the UK Health Security Agency identified eight cases linked to north west or south west London, with a further 13 cases under investigation.

Bathrooms are one of the most important areas to consider when managing Legionella risk because they combine several potential risk factors, including stored water, warm temperatures, infrequently used outlets and fittings that produce aerosols.

A well-designed bathroom should therefore do more than look good. It should also support effective water hygiene throughout the life of the building.

Legionella risk factors

While Legionella outbreaks are often associated with larger systems such as leisure facilities, everyday water outlets also need careful consideration.

The Health and Safety Executive identifies hot and cold water systems, spa pools and cooling systems as examples of purpose-built systems where Legionella outbreaks may occur.

The risk increases where systems:

• Operate within the Legionella growth range of approximately 20–45°C

• Create aerosols, such as showers, spray taps and spa jets

• Store or recirculate water

  
  

Minimise dead legs

Sections of pipework where water can remain unused for long periods are a recognised risk factor.

For example, a bathroom designed with an additional shower connection for future expansion may create a section of pipework where water can become stagnant.

Where future-proofing is required, designers should consider how unused connections will be managed until they are brought into regular service.

Select accessible outlets

Taps, shower heads and spray fittings should be easy to access for routine cleaning, descaling and replacement. Components that are difficult to remove or maintain can discourage effective maintenance and increase long-term risk.

Use TMVs

Thermostatic mixing valves, or TMVs, are commonly specified to provide safe outlet temperatures in settings such as hospitals, schools and public facilities.

By mixing hot and cold water close to the outlet, TMVs help reduce the risk of scalding while allowing hot water to be stored at temperatures that inhibit bacterial growth, typically around 60°C.

Water storage and tanks

Where stored water forms part of the system, tanks should be correctly sized, insulated, covered and easily accessible for inspection and cleaning.

Oversized tanks or poorly maintained storage systems can create conditions that encourage bacterial growth.

Pipework accessibility

Concealed services can improve the appearance of a bathroom, but pipework should still remain accessible for inspection, temperature monitoring and remedial work.

If maintenance teams cannot reach critical components, it becomes much harder to demonstrate that the system is being properly managed.

During construction, pipework may also be installed months before a building is occupied. If water remains stagnant within the system due to construction delays, phased commissioning or low water usage, conditions can become favourable for bacterial growth, particularly during warmer weather.

Compliance after handover

Even the best-designed system requires ongoing management.

Under the Health and Safety Executive’s Approved Code of Practice, ACoP L8, duty holders are expected to assess the risk of Legionella and implement appropriate control measures for hot and cold water systems.

An effective control regime may include:

• Routine temperature monitoring

• Water sampling where appropriate

• Annual inspection of storage tanks and calorifiers, or more frequently where the level of risk requires it

• Weekly flushing of infrequently used outlets

• Cleaning and descaling of shower heads and taps

• Servicing of TMVs at least every 12 months

  
  

Accurate record keeping is also essential. In the event of an inspection, duty holders must be able to demonstrate that monitoring and maintenance have been carried out in line with the agreed control regime.

Most people use bathrooms every day without considering the potential risks, taking access to clean and safe water for granted.

Designers and specifiers therefore have an important role to play in building Legionella prevention into healthy, resilient buildings from the outset, rather than treating it solely as a maintenance issue after completion.

The summer months may be a useful prompt to review water hygiene measures, but effective Legionella control should be embedded throughout the entire lifecycle of a building — from design and installation through to operation and maintenance — to support year-round compliance and safety.