The legionella species of bacteria prefer a temperature of 37°C. This is exactly the same temperature as humans and one of the reasons legionella can thrive inside our bodies.

Legionella bacteria grow fastest at 37°C. They will still grow when the water temperature is higher/lower than 37°C but the rate of growth slows down.

When temperatures are either ~15°C higher (or lower) than their favourite 37°C, they can no longer grow. In fact, they enter a dormant state and can remain in this condition for many months. If the water temperature returns somewhere in the range 20-45°C, the bacteria will become active once again.

What temperatures kill legionella?

• Legionella will die when the temperature drops below freezing point, but that is an unworkable solution.
• The only practical way to kill legionella is to raise the temperature to at least 60°C.

Looking at the chart below, it’s easy to see how legionella reacts to different temperatures.
In simple terms, Keep your hot water HOT and your cold water COLD

What are compliant water temperatures?     

The UK guidelines are based on the chart above.

• For hot water, store it at a temperature where legionella cannot survive and distribute at a temperature which is too high for it to grow.
• For cold water, maintain the supply cold enough so the bacteria are unable to grow.

Hot Water

(within 1 minute of running the outlet)

• Hot water should be stored at 60°C minimum
• If the hot water is recirculated, the return temperature as it enters back into the storage vessel must be 50°C minimum
• In hospital/healthcare premises the return temperature must be 55°C minimum

Cold Water

(within 2 minutes of running the outlet)
All cold water should never exceed 20°C.

Sentinel Outlets

The nearest and further outlets in the building are called “Sentinels”. Your risk assessment and Written Scheme should list the hot and cold water outlets which are deemed your Sentinel points. The temperatures at these outlets should be taken and recorded every month. The records have to be kept for at least 5 years.

If any of the temperatures don’t meet the requirements above (ie they are non-compliant), inform your manager so that they can investigate and rectify the problem.

Hot Water

If you have more than just a single hot water cylinder, and they serve different parts of the building; then there will be separate “Sentinels” for each unit.

Cold Water

If you have more than just a single cold water storage tank, and they serve different parts of the building; then there will be separate “Sentinels” for each tank.

In effect, checking the temperature at the Sentinel locations gives a quick “snapshot” of the whole building. If the water temperature is OK at the first outlet and still OK at the last outlet – there’s a good chance it’s OK everywhere.

Remember, you still need to check the temperature at every outlet, at least once each year.

What happens if a hot water sentinel outlet has a TMV fitted?

It is common for a Sentinel outlet to have a Thermostatic Mixer Valve installed. This will obviously alter the temperature at the outlet.

In these situations the temperature should be taken from the hot water supply pipe before the valve; this is best done using a surface probe thermometer.

Are Thermostatic Mixer Valves (TMVs) a legionella problem?

Taps near to the stored water vessel could easily have a temperature of 60°C. At this scalding temperature, it only takes 5 seconds to cause a 3rd degree burn.

This is a hazard to the young and elderly so TMVs are fitted close to the outlet to provide a safe temperature of 40°C.

If the property has a problem with their hot water so that the max temperatures were only 30°C for a couple of days, then small numbers of legionella would be able to get into the distribution system and colonise the pipework all the way to the outlets.

When the water temperatures return to normal, the legionella would be killed in the storage vessel and pipework. Unfortunately, legionella in the TMV and the pipework & outlet downstream won’t get killed because the temperature doesn’t rise above 40°C.

What’s more, since these temperatures are ideal for growth; the legionella bacteria can proliferate to levels that pose a threat to humans.

This is a hidden danger since all the Sentinel water temperatures can be perfect. This demonstrates the importance of regular legionella testing.

Stay Safe with Regular Legionella Testing

Because TMVs can mask hidden risks in your water system, compliant sentinel temperatures alone aren’t enough to guarantee safety. The only way to truly know if Legionella is present—and prevent potential outbreaks—is through routine, professional water testing.

At Aquacert, we provide UKAS-accredited legionella testing, risk assessments, and expert guidance tailored to your property type, whether residential, commercial, or healthcare.

Call us today on 0800 048 1737 Or contact our team online for a fast, no-obligation consultation.

Don’t wait for a problem to arise, protect your building, your tenants, and your peace of mind with proactive water safety management.

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What happens if you get a positive Legionella result?

Getting a positive legionella result is quite common so it is important that there is a plan to deal with these circumstances.

This plan should be set out in the “Written Scheme of Control”. A Legionella written scheme of control is a comprehensive risk management document identifying the measures required to control your water systems. It is compiled following the legionella risk assessment.
If these documents are not available, you will need to do two things:

1. Implement an immediate plan to eradicate or minimise the legionella in your water system.
2. Make arrangements for the assessment and written scheme to be undertaken by specialists.

What is the risk to people who work/visit your property?

What immediate measures are effective

The post What happens if you get a positive Legionella result? appeared first on Aquacert.

Let’s look at why pre or post flush sampling is important and learn why it may affect the results.

What is pre flush sampling?

For most legionella samples, this is the method that is used.  Simply turn on the outlet and fill the bottle straight away.  The pre-flush sample represents water held within the tap or fitting.

What is post flush sampling?

A post-flush sample with disinfection is water collected after a tap, or fitting, has been disinfected and water has been run to waste.  This type of post-flush sample is intended to be representative of the quality of the water supplied to the tap or fitting.

How can the results be different?

When a property gets a positive result, it’s time to start the detective work to establish exactly where the bacteria are. It may be a single tap, shower or valve which is providing a suitable habitat for these bacteria to live. Alternatively, legionella may have colonised most of the water system.

Example:
AquaCert advise you that the 1st Floor Sluice Room Sink Hot Water Tap has quite a small number of legionella bacteria. Do you disinfect just the tap or the whole building?
One approach is to take further samples, one sample a pre-flush and the 2nd sample a post flush after disinfecting the tap.

How do you disinfect a tap for a “Post-Flush” sample?

If there are both ‘pre’ and ‘post’ flush samples from the same outlet, always perform pre flush sampling first.

• Run the outlet, at least one litre (or until the water runs clear).
• Remove any anti-splash, spray nozzle or flow director device.
• Clean the accessible parts of the tap to remove debris such as scale/corrosion products and general grime.
• Use a syringe or spray bottle to inject disinfectant inside the nozzle of the tap until it runs out.
• Wait for at least 2 minutes for the disinfectant to destroy any bacteria it is in contact with.
• Turn on the tap, adjust to achieve a medium flow rate. Continue flushing the tap to drain for approx. 45 seconds to remove all traces of disinfectant.
• Whilst the tap is still running, fill the sample bottle to the 1000cm3 (1 litre) marker line.
• Invert the sample bottle several times to ensure biocide neutralizing agent is well mixed within the water.

What disinfectant should be used?

There are two common disinfectants types used to sanitise outlets prior to sampling.
Alcohol Based
70% Isopropyl Alcohol

• (also called IPA, 70% v/v ethanol and water or 70% v/v propan-2-ol and water)

Chlorine Based
Approx. 5,000ppm solution

• If you are using household (supermarket) bleach, dilute one part bleach to 9 parts water.
• If you are using industrial bleach (14-15%), dilute one part bleach to 30 parts water.

The post Pre or Post flush sampling? appeared first on Aquacert.

So far, so good …

• Sterile Bottles received.
• Sample locations identified.
• Sample bottle filled; caps screwed on tight.

The project is almost complete, you just need to get the bottles to the laboratory! Luckily, AquaCert make this task really easy.

When to contact AquaCert for a collection to pick-up your bottles

We only pick-up from Monday – Thursday, never on Fridays

AquaCert laboratories process thousands of legionella samples every week. Every bottle looks identical to every other sample, but we can’t risk getting them mixed up!
This is why we need a laboratory submission sheet.

What is on the sheet?

Your order number, our IT system generates this number. When you call to arrange a “pick-up”, we will ask you for this number. As soon as our staff input this into our database, they can see details on past results,
contacts, addresses etc.

As an extra precaution, the same number is printed on the labels of your sterile bottles. This ensures we can process your analysis even if the submission sheet becomes separated from your samples.

The information we need from you is:

• The property where the samples were taken.
• The locations where the samples were taken.
• The date and time you took them.

These details will be input onto your results certificate when the analysis is complete.

And finally …

Put this laboratory submission sheet in the courier bag with the bottles. Let your colleagues know where the courier bag is stored in case you are not available when the driver arrives to collect it.
REMEMBER – The courier can arrive ANYTIME between 8am – 6pm, so have the bag ready by 8am latest.

The post What is a Laboratory Submission Sheet? appeared first on Aquacert.

The post How Do You Take a Legionella Water Sample? appeared first on Aquacert.

• Every property in the UK should have a legionella sample testing and risk assessment on its water services. This report highlights the risks and puts forward recommendations to control them.
• A second document is also required, a Written Scheme of Control.
• The Written Scheme of Control sets out the tasks which are required to manage the risks.
• If legionella sampling is required, the locations and testing frequencies will be clearly documented so they can be part of the overall building maintenance programme.

Unfortunately, it is not uncommon for these documents to be missing, mislaid or completely out of date. If that’s the case, start the process to get a specialist company to provide these reports.
In the meantime, AquaCert can provide an example and general guidance on where to take samples.

EXAMPLE

Large Care Home

Legionella bacteria need to get into our lungs to cause the illness (Legionnaires’ Disease). Aerosols containing the bacteria are the principal route for an infection.

Now you can turn this information into a sampling protocol

The post Where Do You Take Legionella Water Samples? appeared first on Aquacert.

The Traditional Method

When it comes to different types of Legionella testing, this long-established method of culturing the bacteria remains the ‘gold standard’ of analysis. Since it detects all species of the legionella family, additional tests can determine whether the strain found is one of the most pathogenic varieties. Pathogenic strains pose a greater risk to health.

• Detects only viable bacteria (those capable of reproducing).
• Detects all Legionella species.
• Results typically reported in colony forming units (cfu) per volume, limit of detection (tLOD) is 10 cfu/L on a 1 litre sample.
• Yields isolate for additional characterization
• Incubation takes 10 days
• Requires skilled technicians to follow laboratory method statement
• Better for evaluating growth trends

PCR Method

Polymerase Chain Reaction testing is a molecular biology technique in which the DNA of a microorganism is extracted and then amplified. Since the result includes both dead and alive legionella, it is difficult to determine what risk is posed to human health.
In extensive water systems (e.g. large hospitals), PCR tests can quickly help determine if legionella contamination is contained to a single area/ward or is widespread throughout the establishment.

• Detects Legionella-specific DNA or RNA.
• Does not differentiate between live and dead bacteria.
• Results typically reported in genomic units (GU) which are not directly equivalent to cfu.
• Rapid analysis takes just 2–48 hours to get a result.
• Is useful for negative screening.
• Good at evaluating whether remedial actions are successful.

Conclusion

It’s great that there are two types of Legionella testing methods and they have different benefits.
For most situations where you are testing (and expecting no legionella), the traditional culture method is the best choice.
If you have a known problem with legionella contamination, then PCR can be a very useful method of monitoring the success of the actions taken to reduce/eliminate the bacteria.

What new methods are being developed?

Antigen Testing

We all remember the lateral flow tests we all did during COVID, the same technology can detect legionella bacteria. This sounds great, a simple test that gives a result in a few minutes – but there are still a few technical issues to resolve yet.

• At present the sample preparation prior to dripping onto the cassette is long winded. It needs to be simplified so users don’t require training to accomplish it.
• Current technology is sensitive to Legionella pneumophila serogroup 1. An improvement would ideally show the other major pathogenic strains which can cause fatalities.
• The test can’t easily determine any difference between living or dead legionella bacteria.

Once these downsides are improved, this technology will transform legionella testing completely.

Want to stay ahead of the curve or need support with Legionella risk management? Contact Aquacert to discuss testing solutions, compliance support, and how we can help keep your systems safe.

The post Types of Legionella Testing appeared first on Aquacert.

Chapter 1

Legionella Testing Explained Simply

1. What are Legionella Bacteria?
2. Where do these bacteria live?
3. How dangerous are they?

Although legionella bacteria have probably been around for many thousands of years, they were only discovered and named 50 years ago.
Legionella are a family of bacteria (at least 60 different species) which live predominantly in water. In cooler waters, such as rivers and lakes, their concentrations are very low and do not pose a risk to humans. When the bacteria get into man made water systems where the temperatures are between 20-45°C, they can proliferate quickly.
The most common sources of legionella are:

• Cooling Towers
• Showers
• Water Features
• Fountains
• Irrigation Systems
• Ice Machines
• Swimming Pools
• Hot Tubs
• Domestic Water Systems
• Water Features
• Dental Water Lines
• Fire Suppression Systems

Legionnaires’ disease is a serious type of pneumonia which can occur when legionella bacteria are breathed into our lungs. The route into our lungs normally happens when the bacteria contains minute water droplets. These water droplets or aerosols are produced from showers, hot tubs or even just running a tap. Occasionally legionella bacteria can accidentally reach the lungs when someone chokes while drinking.
Some species of the legionella family are more dangerous than others. The strain Legionella pneumophila serogroup 1 causes the most fatalities. Up to 10% of the people who contract this particular illness will die. The people who are at greatest risk are:

• People 50 years or older, especially men
• Current or former smokers
• People with a chronic lung disease (like chronic obstructive pulmonary disease or emphysema)
• People with weak immune systems or who take drugs that weaken the immune system (like after a transplant operation or chemotherapy)
• People with cancer
• People with underlying illnesses such as diabetes, kidney failure, or liver failure

Can you treat Legionnaires’ disease?

If caught soon enough, the majority of people will respond to antibiotics and make a full recovery.

Are legionella bacteria difficult to kill?

All species of legionella bacteria can be easily and quickly killed by common disinfectants or simply raising the water temperature. Elevating the water temperature above 60°C will kill the bacteria within a few minutes, at 70°C they are destroyed almost instantly.

How difficult is it to test if legionella bacteria are in a water supply?

Our laboratories test thousands of water samples every day, so we’re more than qualified to provide you with the answer to the question “What is Legionella testing?” If you want your water tested, AquaCert will send you a suitable, sterile bottle. You fill it with the water you want testing, AquaCert will send a courier to collect the bottle from you and deliver it to the laboratory for analysis.
So, you fill the bottle, we do the rest.

Stay Ahead of the Curve with Expert Testing Solutions

Keep your water systems safe from Legionnaire’s Disease by testing regularly for Legionella bacteria. If you require professional testing services or need expert support with compliance and Legionella risk management, contact us at AquaCert.

The post Everything You Need to Know About Legionella Testing appeared first on Aquacert.

We’ll start with the basics.

Chapter 1: Legionella Testing Explained Simply

1. What are Legionella Bacteria?
2. Where does this bacteria live?
3. How dangerous is it?

Chapter 2: Types of Legionella Testing

1. The traditional culture method is currently the gold standard but for how long?
2. qPCR is quicker but is it better?
3. What may future legionella testing look like?

Chapter 3: How do you take a legionella sample?

1. A simple, straightforward guide of how you collect a water sample for legionella analysis.
2. If it’s this easy, why have we been paying so-called “experts” so much in the past?

Chapter 4: Where do you take a legionella sample?

1. How do you choose a suitable location?
2. Are there locations you should never test?

Chapter 5: Completing the submission sheet

1. This is the form you send to the laboratory, it tells them the info they need to have so they can test the sample.
2. What information does the laboratory need?
3. Why do they need to know the time the sample was collected?

Chapter 6: Pre or Post Flush Sampling?

1. What is the difference between a pre-flush sample and a post-flush sample?
2. Will the results be different?
3. What do the different results tell me?

Chapter 7: What happens if the legionella results are positive

1. About 5% of the water we test has active legionella bacteria in it – help!
2. What is a bad result?
3. What is a really bad result when testing for legionella?

Chapter 8: How to disinfect your water systems

1. What is the best disinfectant to use?
2. What concentration do I need?
3. How long does it need to be in the water?
4. How soon after a disinfection should I re-test?

Chapter 9: Point-of-Use Legionella Filters

1. Do they work?
2. Where do you fit them?
3. How long will they last?

Chapter 10: How to test Swimming Pools

1. What tests are required & how often?
2. Does it matter where in the pool I take the sample?

Chapter 11: How to test Hot Tubs

1. Do they have to be tested every month?
2. Why are my results always poor!

Chapter 12: How to test Cold Water Storage Tanks

1. What is “Drinking Water Quality”?
2. Why are there no fixed maximum levels for TVCs?
3. Do I test a tank for legionella?

Chapter 13: How to test calorifiers & hot water cylinders

1. How do you get a sample from a cylinder?
2. The drain valve is seized, what should I do?

Chapter 14: How to test drinking water units

1. Shouldn’t the quality from these units always be perfect?
2. Why are the results always worse than ta water?

Chapter 15: How do you take a water sample from a shower?

1. How do you get the water into the sample bottle?
2. Can I remove the shower head to make sampling easier?

Chapter 16: How to test an ice making machine

1. Surely no bacteria can survive in ice?
2. How do I collect a sample?

The post Welcome to the Ultimate Guide to Legionella Testing appeared first on Aquacert.

In 2015, New York City earned the unenviable distinction of recording the worst Legionnaires’ disease outbreak in the state’s history. After the dust settled, a total of 16 deaths and 133 infections were recorded. This prompted state and city officials to take decisive steps to curb the spread of the disease.

The worst may be far from over.  The Alliance to Prevent Legionnaires’ Disease (APLD) issued a statement.  They declared that the number of recorded cases of the disease continues to climb steadily. In fact, in 2017, the city recorded 441 cases, equivalent to a 64% increase from 2016 when a total 268 cases were reported. What is even alarming is the fact that NYC’s situation becomes graver when compared to state statistics.

The total number of cases recorded in the city accounts for roughly 44% of the state total.

Worse, the record is the highest in the United States. However, state and city officials reasoned that the massive spike in the number of recorded Legionnaires’ disease occurrences in New York City can be partially attributed to:

• The increased awareness of residents.
• Improved testing and risk assessment for Legionella
• A massive overhaul of the city’s reporting system.

Officials added that compared to other parts of the country, NYC boasts of an aggressive campaign when it comes to following up on reported cases of the disease. This is in response to the Legionella outbreak in the Bronx area in 2015. Since then the state’s Department of Health has conducted regular checks on both cooling towers and drinking water systems in health care facilities.

During this outbreak, about 57% of the cases where traced backed to health care facilities. However, advocacy groups like the APLD say that the actions of the state and local units should not stop at just monitoring cooling towers and drinking systems. These groups argue that equal attention should be given to monitoring public water systems. These are the source which carry water into residences and commercial spaces. According to available data, 35% of the reported cases of Legionnaires’ disease can be traced back to the contamination of public water systems.

Additionally, APLD enjoined state and local officials to take a proactive stance in its approach to stopping Legionnaires’ disease. So instead of reacting to outbreaks they hope to deliver an holistic and systematic approach from water distribution to consumption.

Legionella Outbreak In Quebec City, Canada

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