Legionella Monitoring

Legionella can cause potentially fatal cases of Legionnaires’ disease, making it a serious risk in nearly every situation it is discovered. Of course, this means that managing your water systems correctly is important, especially as a business owner.

Proper Legionella monitoring procedures are important for avoiding potential Legionella exposure. Considering the dangers involved, implementing effective Legionella control measures can be the best way to ensure that your water systems are safe to use.

Legionella Risks 10 things you should know desktop 1

But how do you monitor and contain the spread? While monitoring in the usual sense may not be as much of an option, there are still a lot of ways to make sure that your system is not being overrun and that you are not putting anybody in danger when they use your water supply.

Simaxx can be an integral part of monitoring key temperatures in the control of Legionella, providing you with even more options for monitoring its spread. Being better-equipped is the easiest way of stopping Legionella growth early.

What is Legionella Bacteria?

Legionella is commonly found in water, multiplying at temperatures between 20-45 °C. If inhaled through airborne water droplets created by water systems, Legionella tends to cause Legionnaires’ Disease, a fatal type of pneumonia.

Legionnaires’ Disease does not discriminate and can target anybody if they are given enough exposure. It appears on both residential and commercial properties, spreads to everybody whenever possible, and can only be controlled through outside means.

While it is easy to look up the disease and hit enter on the first result you find, the truth is that Legionnaires’ Disease is a serious risk to everybody. All the research you will find will tell you the same thing – it needs to be prevented before it can kill multiple people in a short span of time.

Identifying Legionella Bacteria

a person getting a glass of water from the tap rather than drinking bottled water 2

It is possible to test for Legionella in water by taking a sample and sending it to a professional lab. Alternatively, certain DIY test kits are available, although these will do nothing to treat the existing Legionella bacteria in water.

Identifying it visually is not an option, given how the virus travels. However, in many unfortunate cases, it first manifests as the virus itself inside a host that has unknowingly inhaled the water droplets carrying it.

There are treatments and ways to help those infected by Legionnaire’s Disease. However, the best protection is to prevent it from ever spreading in the first place, and that means being prepared ahead of time.

Controlling Legionella Bacteria

Putting the right Legionella control measures in place is important for keeping your water systems clear of Legionella. Proper Legionella testing and Legionella monitoring options can also provide a range of benefits for tackling other diseases that spread in the same way, making it a great safety measure.

Remember that there is not an exact way to fully control the spread. In the end, you will still eventually need to kill it off since the risk of letting it spread through your water supply and systems can be far too serious to try containing it in an old water tank or filtering it out yourself.

Temperature Control

The main method used to control Legionella levels and prevent Legionella growth is through temperature control. Like most bacteria in water handling systems, Legionella requires specific conditions to grow well, and disrupting its natural environment can help a lot.

Hot Water

If you suspect that there are Legionella bacteria in a hot water source, store that hot water in a hot water storage cylinder at above 60°C. The water itself should be distributed at 50 where possible.

Cold Water

In cold water, you can get control of Legionella bacteria by storing and distributing the water at below 20°C. Cold water storage tanks also tend to reduce the spread of the bacteria since there is less evaporation and thus fewer tiny water droplets created.

Stagnant Water

Stagnant water increases Legionella risk systems-wide. Good Legionella control means eliminating stagnant water from your water system where possible. This includes removing dead legs and other necessary parts of your cold water systems.

Water Storage

Ideally, you want to turn all water into either hot or cold water while storing it. Consider using cold water storage tanks – appliances that operate at room temperature are still linked to your water system.

The exact cold water systems you use depend on the exact scenario you are in, so be sure to evaluate your existing cold water systems and hot water cylinders to make sure that they are all suitable for this kind of use.

Other Methods

The threat of Legionnaires’ Disease, especially in people who already have serious conditions like respiratory issues or kidney disease, is serious. There is a range of ways to tackle Legionella and Legionnaires’ Disease, both long-term and short-term.


Copper and silver ionisation is one method of dealing with Legionella, and another is using a biocide like chlorine dioxide. In this case, the chlorine dioxide acts as an effective biocide by killing off the threat directly, but only if used in the right quantities and places.

Cleaning chemicals can also make it harder for the disease to actually spread since there will be fewer places to pose direct risks to residents or other uses of the building.

Water System Cleaning

Practice good water hygiene and clean your water system often. Legionella control relies on good water hygiene, and you want your water system to remain clean to prevent build-up.

Routine Checks

Check the distribution temperatures of your water system at least once per month. Check the hot water cylinders once per month and your cold water systems at least once every six months.

Simaxx provides continuous monitoring of critical temperatures necessary for the control of legionella, and ensures that the process of monitoring the temperatures is done in accordance with UK HSE guidance / approved code of practice (ACOP  L8).

legionella main 02

Legionella Risk Assessment

Legionella risk assessments are a legal requirement under the Health and Safety at Work Act 1974. Building managers are required, by health and safety law, to perform a Legionella risk assessment whenever necessary.

When do you perform a risk assessment?

Originally, risk assessments were performed twice per year. Now, the assessment continues until all risks identified have been dealt with for the near future.

It would be best if you carried out an assessment during times where Legionella risks are more common, such as:

  • A change in building use.
  • After alterations to the water system.
  • When Legionnaires’ Disease and/or Pontiac Fever has been reported in nearby residential or commercial properties.
  • If you discover dangerous levels of bacteria in the water in your own property.

What does a Legionella risk assessment involve?

Legionella monitoring risk assessment requires you to look at previous records of disease control and compare them to your current records. This is to help compare the bacteria counts for any worrying changes.

Physical Assessment

The physical assessment means a physical inspection, followed by a consultation to discuss ways to get control of Legionella bacteria in water systems. This may also include maintenance and compliance checks.

idexx receives uk acceptance for legionella 2 1

Storage Assessment

The other risk systems focus on water storage. This means trying to reduce risk to any water storage areas, from a cooling tower to a simple storage tank. Even appliances with low levels of water, like hot tubs, can be worth inspecting.

Which Areas Matter?

Legionella monitoring and risk assessment cover six key areas of Legionella control and safety. Tackling all six makes stunting Legionella growth much easier since they provide a clear overview of how the bacteria is spreading and how it can be stopped.

Inhabitant Risk

How much risk do the Legionella bacteria pose to the residents? Social housing may have older or weaker residents that could be more susceptible to Legionnaires’ Disease, and an office could have many people using the same water sources.

Water Systems

Are the cold water systems and hot water systems mains-fed, storage-fed, using a combination of both, or fed through some other means? This is important for preparing proper control services that need to target every source at once.

More importantly, is there any way for outside debris, vermin or foreign matter to get inside the system? If so, is this a compliance issue, and how can it be avoided to prevent Legionella growth?


As mentioned earlier, recording temperature information allows for far better control of the bacteria. This highlights the areas at the most risk and points out areas where the bacteria may not be able to spread due to excessively high or low temperatures.

Remember that the bacteria in water systems do not necessarily die the moment it drops past their temperature limits. Safety legislation requires specialised steps to remove the risk of Legionnaires’ Disease.

Hot Water System

What kind of hot water systems do you use, and how insulated are they? These require special attention compared to cold water since hot water systems often draw water from a range of sources.

Other Risk Systems

What other risks are there? Are showers and valves installed as expected? How much redundant pipework is in place? Are the property’s water systems flushed often, especially in areas that do not see constant use?

All of this needs to be written down. This usually gives you an idea of what your Legionella control methods need to target first and the kind of Legionella control services you should be looking into.

Who is Responsible for the Control of Legionella Bacteria?

The duty for control of Legionella bacteria in the water is not a pleasant one. Somebody within the building – usually a health and safety specialist or the building owner – has a legal responsibility to prevent Legionella build-up. This is the duty holder.

This person needs to work under the regulations of the Legionella Control Association to audit the situation and ensure compliance. Whoever this specialist is, it is their duty to control Legionella spread, removing any substances hazardous or dangerous to human life in the process.

Assessing Risk

The person responsible for managing Legionella needs to carry out the risk assessment work. While they can have a support team or extra staff members working alongside them, these duty holders may also employ specialised Legionella control services while retaining compliance.

Legionella Management

The top priority of a duty holder should be to clear the Legionella and prevent any spread of Legionnaires’ Disease, all according to relevant health and safety techniques under an approved code of practice.

For more details about the specifics, look into the documentation of groups like the Legionella Control Association.


Legionella Control Services

Third-party Legionella services are an effective way to get large-scale protection and support during serious outbreaks of Legionnaires’ Disease. Even outside of large-scale spreads of the disease, relying on services like this can help to minimise risks.

Professional options like Simaxx can be an excellent choice. Simaxx provides the monitoring to mitigate Legionella risks and provides rules in line with ACOP L8, as well as providing a vast range of monitoring and reporting tools that can fit with any business.

By handing off responsibility to these services – which is allowed – a safety specialist can ensure that all of the right services and methods are employed quickly and effectively. The risk of Legionnaires’ Disease spreading to cooling towers and other cold-water appliances can sometimes be too great to ignore.

Using these services also means that you are not personally required to handle every step of the project, something that can take a long time in larger properties. Office buildings routinely hand off their control options to third-party services specifically because of the huge workload involved.

IMG 2148

Leaving your system untested and untreated can be a massive health and safety risk. The disease will impact people of any health and specifically target those already in poor health, meaning that nobody will be safe until you clear up your system.

Simaxx improves the reporting accuracy and risk assessments of legionella control in hot water systems. The automated rules and report templates eliminate labour-intensive processes.

Data Capture

Hot Water System temperatures and occupancy schedules can be captured from a site Building Management System or IoT wireless solution.

Compliance Monitor

Simaxx automated analytic rules are based around ACOP L8 requirements for Legionella Monitoring and create email alerts when the system falls outside guideline requirements. This ensures that data is being evaluated continuously and corrective action requirements are highlighted.

Report Templates

Report on outcomes of legionella reporting. Provide weekly, and monthly reports for Governance. Easy to output from stored templates.

Case Study: Aquaportal

Legionella monitoring graph temperatures