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What is Legionella Bacteria

Legionella Bacteria | Legionellosis | Legionnaires’ Disease

Legionnaires’ Disease


Legionnaires’ disease, also known as Legionellosis, is a type of pneumonia, which can potentially be fatal although it varies in severity from case to case. Those most at risk are the elderly and the very young, male over 50’s, the ill and smokers to name a few. Legionella bacteria can also cause other, less harmful illnesses such as Pontiac fever and Lochgoilhead fever, which can affect all people.

The main route of infection is through inhalation, by inhaling airborne water droplets that contain Legionella Bacteria. It cannot be spread from person to person and the majority of cases or outbreaks of the disease have been via domestic water systems, evaporative cooling towers, poorly maintained artificial water systems and spa pools.

In basic terms, the more the legionella bacteria is allowed to grow given favourable conditions, the higher the risk is of someone contracting Legionnaires’ disease and falling seriously ill. It is crucial therefore to take correct measures to control the growth of the bacteria and assess the risk of infection as outlined in the ACOP L8 guidelines.

Questions about Legionella Bacteria & Legionaries Disease?

Your Responsibilities


As an employer or a person in charge of the premises, you are legally responsible for health and safety and need to take the right precautions to reduce the risks of exposure to legionella bacteria. This includes making sure that you have carried out a proper legionella risk assessment, actioned all identified risks within the risk assessment report with remedial works, taking water samples to check for any legionella bacteria presence and carrying out ongoing record-keeping in a scheme of control. Legionella training is also a mandatory aspect of any legionella control programme.

You must understand how to:


  • Identify and assess sources of legionella bacteria risk
  • Manage any legionella bacteria risks
  • Prevent or control any risks
  • Keep and maintain the correct records and carry out any other duties you may have

Protect Against The Risk of Legionella Bacteria


The Legionella bacteria tends to live and thrive in water systems at temperatures of 20 to 45 degrees Celsius (optimal is 35 degrees Celsius). Other contributing factors to the environmental spread of Legionella growth are things like water being stored in a tank and/or recirculated, stagnant water, dead legs in the pipework and the presence of deposits in the water system such as sediment, biofilm, algae, scale & rust. Poor understanding, knowledge and training can also play a big part in the growth of Legionella which is why it is so important to understand what it is, how it grows and what you should do to protect yourself and others against the risk of Legionella.

uRisk is a specialist water hygiene company that offers a full suite of services including ACOP L8 Risk Assessments, Legionella testing, water tank cleaning, temperature monitoring onsite & remotely and remedial services to help get your water system in the best place possible. We also provide chlorination and disinfection to treat the water which has proved to be very effective at killing the bacteria and the prevention of Legionnaires’ disease.

As stated above, the bare minimum legal requirement is to undertake a full and proper legionella risk assessment to establish the condition and safety of environmental water system if you are a landlord, a person in charge of the premises or a health & safety officer. However, we don’t recommend taking a bare minimum approach to air & water hygiene as the consequences of infection can be serious & fatal. The good news is that we can help you to stay on top of all of this and put a good set of control measures in place to ensure that you are doing everything possible to prevent the risk of infection.

All of our services are competitively priced and our team of experts are on hand to help you if you have any questions.


Treating Legionella In Water Supplies


If Legionella bacterium is detected in the water supply then remedial works will need to be undertaken to remove the risk of infection and bring the system back in line with best practices. This may involve removing dead legs/dead ends in the pipework, flushing stagnant water, cleaning the water tanks, reducing the number of outlets and monitoring water temperatures to ensure that cooling or cold water is stored below 20 degrees Celsius and hot water is at 50 degrees or more. Chlorine has been proven to be very effective in killing the bacteria as part of an overall treatment programme.

Further Reading & Resources


We have written lots of other great content around what Legionella is, how to control the risk of infections and more of what you need to know to keep safe over in our blog section with some popular posts below for you to take a look at:


Why choose uRisk?

25 Years Experience

Over 25 years of water hygiene and legionella control experience.

Customer Service Excellence

Friendly and simple advice by phone, email & online at your convenience.

City & Guilds Qualified

All staff are trained water hygiene consultants and engineers.

Nationwide Coverage

With engineers located all across the UK, we’re never too far away.

UKAS Accredited Testing

Our labs are UKAS approved providing you with quality assurance.

Full Compliance Services

Your one stop shop for legionella control, no need to go elsewhere.

Legionnaires’ Disease FAQs

Where can you catch Legionnaires disease from?

You can catch it from things like:

  • showers, taps and toilets
  • spa pools
  • hot tubs
  • cooling towers
  • water tray air conditioning units
  • fountains, land other areas that cause aerosols/spray from water
Where don't you get Legionnaires' disease from?

You don’t normally get infected from:

  • drinking water containing the bacteria
  • other people with the infection
  • environments like ponds, lakes and rivers
What are the symptoms of Legionella or Pontiac Fever?

The symptoms of legionella outbreak are flu like and can cause severe respiratory issues & bad coughs. The NHS says that you should contact your GP if you have “a bad cough and:

  • it does not go away
  • you cannot breath properly
  • you have severe chest pain
  • you have a high temperature or feel hot and shivery
  • you feel like you have the flu

These could be symptoms of legionnaires’ disease. Call 111 if you are unsure and they will tell you what to do. They can arrange a phone call from a medical nurse or doctor if you need one.

Go to or call 111.

Do I need testing, a risk assessment or both?

A competent person should undertake a legionella risk assessment. This is someone who has experience and/or qualifications in legionella risk assessing and can provide evidence related to the understanding the risk of legionella in water systems.

Undertaking a legionella risk assessment includes assessing health of your water system designs, materials, temperatures, stagnation, purpose of supply and it’s usage to name a few.

It is strongly recommended that a professional carries out your legionella risk assessment particularly if you are unsure of your health and safety obligations. A template risk assessment will not be able to guide you through your related compliance needs alone.

Can I get Legionnaires from my Shower Cooling Towers or Water Systems??

In short, yes! It’s not necessarily the shower that causes bacterium legionella pneumophila growth, but it is a high risk area to contract the infection. Conditions such as limescale presence, infrequent use and temperatures between 20-50°C may encourage bacterial growth at the shower. But these related conditions anywhere in the water system may lead to the potential growth and form of legionella outbreak in the contaminated shower head.

How does a person catch Legionnaires disease?

Normally Legionnaires’ disease is contracted through inhalation of fine droplets in the air or aerosol which infect your lungs. This is typically through coming in to contact with a water system containing or contaminated by Legionella presence. Bacterium legionella pneumophila is a form of pneumonia and the health of your immune system is impacted dramatically. Legionella infections materialises in the from of fever and disease.

How do you test for Legionella Bacteria?

Firstly, if you think you have Legionnaires’ disease because of the symptoms highlighted above, contact your GP immediately. They will most likely take a urinal sample to confirm if the bacteria is present.

Secondly, to test for legionella in a water system sampling is required. Sampling is undertaking by running water into a sterile bottle which is then sent to a UKAS accredited lab to be cultivated. For more on legionella testing visit our legionella testing page.

How common is Legionella Bacteria?

Centers for disease control and prevention currently state there are hundreds of reported outbreaks caused by legionella in the UK each year. However, our lab predicts that there are currently 1 in 25 legionella samples that are positive. Whilst the is a relatively low number of reported legionella cases, this is likely due to the lack of knowledge about the bacteria with misdiagnosis. Furthermore, legionella positive results are not the same as an outbreak. There are many positive results each month that are not considered outbreaks until 2 or more persons have been confirmed as infected with Legionnaires’ disease from a particular source.

How much does a Legionella risk assessment cost?

All assessments vary in prices depending on the number of water outlets, cold water storage tanks, hot water cylinders, combi boilers and other water systems assets that may be present. Your water systems assets will determine the time spent on site.

There are two types of assessments, the first is commercial and the second domestic, also referred to as residential rental properties or landlord risk assessments.

Commercial risk assessments normally start from £250 to in excess of £750, however our prices start from £99 depending on the size of the water system and location.

Domestic risk assessments can range tremendously with a number of plumbers, gas engineers and other tradesmen offering these assessments without the specialist training, it’s important to check that your assessor or engineer is properly qualified. Our prices start from £55 for multiple landlord properties to £95 for single landlord properties. Our prices for residential rental properties are based on the property being no more than 5 bedrooms.

How long does it take to get the results from a Legionella test?

Legionella testing takes 14 days, this allows the bacteria to be cultivated and meet requirements set in place by UKAS for the correct bacteria testing conditions. Once the testing is completed the reports are produced by our team thereafter. Results are sent as soon as they become available and have been reviewed.

Which locations do uRisk cover?

uRisk covers the UK from the deepest depths of Lands end to the hefty heights of John O’Groats and including Ireland.

With engineers scattered throughout the UK we’re always a hop, skip and a jump away, rest assured we can get to you at any time of the year.

As a service provider our office location has little relevance. More so now than ever before with ever changing technology. Whether you need help via our support ticket system or a quick phone call or email, you can rely on uRisk to provide a professional and reliable service.


This is by far the best service I have received in a long time.Lloyd who we spoke to was super helpful and very thorough with everything.I would def recommend using this company, they are not just out for money they put their customers needs first.Thank you
Coral Dawkins
Coral D.
Incredibly detailed and professional team. Have been beyond helpful with with our CQC legionella compliance for our Safety. They’ve found solutions to fit around how we work and our budgets. We are always advised with reference to HSE which has been brilliant.
Amy Thorne
Amy T.
Richard & Nick are great. Really good work and nice people.
Joshua Ballard
Joshua B.
uRisk have been helping us with our Legionella Control for a number of years now. We've recently had a CQC audit and they were very impressed with our legionella compliance! Thank you for all your help.
Mike Port
Mike P.
Brilliant company, customer service was great! And engineers were fantastic. Thanks again uRisk! Will definitely be using them for all future work.
Nikesh Gohil
Nikesh G.
Extremely happy with our legionella risk assessment carried out by uRisk, easy to understand and great customer service. Thanks again
Nickayla Robertson
Nickayla R.
We have been working with Urisk for best part of year now. I could not recomend their services highly enough. They always promptly respond to our requests promptly and manage the job from start to finish seamlessly. I would highly recommend.
Sam Guest
Sam G.
Really easy to organise a risk assessment to be carried out at our offices and have had great help from them since to implement the necessary changes to keep the office safe. Would definitely recommend.
Holly Ferguson
Holly F.
A fabulous company, excellent customer service, they try to accommodate appoitments, and do there utmost in emergencies, been with them a few years now,  honestly cant fault them. Coming out of Covid 19, having our building urgently disanitised,  big thank-you to Luke and Lee for staying so late to get the job done!! Thank you Devon, for juggling the diary to fit us in so soon. A Team 🙂
Jo Maskell
Jo M.
Daniel did the testing today at PGHC He was really efficient, friendly and so professional. An absolute pleasure to deal with. Thanks Daniel
Lorraine Carruthers
Lorraine C.
Brilliant Service, efficient, professional, punctual and friendly.
Alex Windsor
Alex W.
My experience with URisk Water Hygiene from my initial enquiry, to their site visit to undertake a Legionella Water Risk Assessment at my office (MDG), to providing me with the report and aftercare has been superb! Efficient response times, excellent customer service, friendly, helpful advisors and assessors who are always ready to help and provide guidance. An absolute pleasure to deal with, I highly recommend!
Lauren Wakeman
Lauren W.
Brilliant service! Thanks a lot for the hard graft
Leon Macauley
Leon M.
My first time using Urisk for work at multiple sites. Daniel was absolutely brilliant, polite and professional. Highly recommended! 🙂
Claire Keay
Claire K.
We're a small GP practice and started using uRisk for legionella risk assessments. We opted to use their remedial and monitoring services and they've been absolutely great. We cannot recommend them enough! Thank you so much!
Amanda Pates
Amanda P.
Fantastic training courses and we've found the legionella risk assessment very easy to read and far more detailed than any we have previously had. 5 star service!
Gemma Pond
Gemma P.

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