5 Ways to Prevent Legionella

Legionella is a type of bacterium which thrives in warm, stagnant water, which includes pipework, showers, hot tubs and HVAC (Heating, Ventilation and Air Conditioning) systems: basically, anywhere that water can be left to stand for too long. When this bacterium is inhaled in an aerosol, or vapourous form, such as steam in a shower or hot tub, it can cause Legionnaires’ disease, which is a potentially life-threatening illness, especially for vulnerable individuals.

The duty holder for each premises has a legal duty to ensure the health and safety of all people using the property and is responsible for managing risks and preventing Legionella exposure . There are various practical ways to help prevent the bacteria from causing a threat to the people using the building and to ensure you stay compliant, as preventing Legionella is not only a matter of public health, but also a legal obligation under UK legislation. This guide will unpack some of these practical steps to prevent Legionella from spreading in your water systems.

1. Maintain water temperatures

Temperature control is one of the simplest and most effective control measures that can be implemented to keep your water systems safe. There is an optimum temperature at which Legionella bacteria multiply rapidly, and this is between 20°C- 45°C, with the optimum temperature being at 37°C – human body temperature. In large buildings, such as hospitals, schools, care homes and some industrial facilities, hot water is frequently stored in hot water tanks, creating the perfect environment for the multiplication of bacteria, unless the water is kept at a minimum of 60°C so that it reaches 50°C within one minute at all outlets. Cold water should be kept below 20°C throughout the system, and regular temperature checks at sentinel points can help to monitor these temperatures, prevent Legionella from multiplying and ensure safe conditions. Thermostatic mixing valves can also be fitted to help ensure consistent, safe temperatures.

2. Proper water system design

A poorly designed water system can have problem areas where water can be left to stagnate, called ‘dead legs’, such as a stretch or section of pipework that’s longer in use but still connected to the water system. As water isn’t flowing through it regularly, it can easily become a breeding ground for bacteria, so having a plumber remove any ‘dead legs’ will ensure water flows freely throughout your water system without becoming stagnant. Effective water system design reduces stagnation and nutrient buildup, such as organic matter, corrosion products, scale, sediment and other items, that can leach into the water and feed the bacteria. Fitting your cold water tank with air-tight lids and insect screens will help prevent external contamination from dust, insects or other debris. Ensuring your water system is inspected and assessed by a professional will help prevent Legionella from building up in your water systems.

3. Regular cleaning and disinfection

Another way to prevent Legionella is to make sure that your water systems are regularly and thoroughly cleaned and disinfected. Legionella bacteria thrive in biofilms, which accumulate in scale, sediment and corrosion deposits. These contaminants form over time in tanks, pipework and outlets, providing perfect breeding grounds and also making water systems less efficient and increasing risk. High-risk environments, such as properties where vulnerable individuals are present, need to have chemical disinfection, with chlorine dioxide, or thermal treatment, where the system is superheated to above 60°C, killing bacteria. Other cleaning should include:

· Shower heads, taps and hoses: remove scale and sediment buildup

· Storage tanks: remove scale and disinfect regularly

· Flushing infrequently used outlets: keeping water moving throughout the system

Professional cleaning, paired with a thorough risk assessment, will ensure every possible contamination point is checked and processed.

4. Monitoring and testing

Large or complicated systems in vast buildings need to implement more than just temperature control and flushing out taps regularly. A proper water treatment and maintenance programme must be developed and maintained according to the risks of the individual property or institution. Regular testing should be part of your risk management strategy, especially in healthcare organisations or where prior contamination has occurred. Routine checks should include temperature monitoring at sentinel points, inspection of tanks and pipework as well as sample testing. Regular risk assessments are essential to identify any changes in use, system design or building occupancy that could increase risk. Some common treatment options can also be implemented to neutralise bacteria, avoid biofilm formation and prevent Legionella reproduction. Some of these treatments include:

· Chemical dosing

· Filtration systems

· Ultraviolet disinfection

The monitoring and testing element is not only advisable, but is also legally required under ACoP L8 and HSG274, especially for high-risk premises such as hospitals, health facilities, care homes and schools.

5. Documentation and compliance

Keeping accurate records is an essential part of maintaining compliance and part of any Legionella control strategy. The regular monitoring should include:

· Logs of maintenance tasks – such as flushing, descaling, disinfection and temperature checks

· Records of Legionella risk assessments

· System modifications or upgrades

· Water testing results

· Training of staff or anyone involved in control measures

· Assessments of potential hazards, the condition, design and usage of the system

These records and assessments should be updated annually, but also after any significant system alterations or changes of use for the building. Keeping proper records shows commitment to comply with the Health and Safety Executive (HSE) requirements under the Health and Safety at Work Act, 1974 and COSHH (Control of Substances Hazardous to Health), 2002, along with the previously mentioned ACoP L8 and HSG274. Keeping meticulous documentation of your organisation’s efforts to prevent Legionella is admissible in a court situation to prove evidence of due diligence and compliance.

Why prevention is better than cure

Preventing Legionella is always the most effective and cost-efficient way to avoid the issues of handling an outbreak. The health implications can be severe, especially for properties with high-risk individuals, where the risk to life can be high. An outbreak can also result in fines and legal penalties, temporary business closures and reputational damage. Taking proactive steps will mean meeting compliance obligations to prevent Legionella and also demonstrate a commitment to safety and responsible building management.

Stay compliant and stay safe

Preventing Legionella is a legal and moral responsibility, and by following best practices, such as the five simple steps outlined in this guide, you can protect both people and property. Temperature control, flushing systems, professional water treatment and risk assessments will provide the comprehensive and ongoing approach necessary. If you’re unsure about your current compliance level, it’s wise to seek professional support, and a Legionella risk assessment is the best place to start, so book a risk assessment and begin your journey to prevent Legionella.