• Twitter
  • Facebook
  • LinkedIn
  • Mail
  • Call Me Back
  • About
  • Knowledge
📞 Call us on 0330 223 31 31
Water Treatment Services
  • Home
  • Water
    • Applications
      • Boiler Water Treatment
      • Cooling Water Treatment
      • Closed Loop Water Treatment
      • Legionella Control
    • Services
      • Cooling Tower Cleaning
      • Cooling Tower Maintenance
      • Chlorine Dioxide Water Treatment
      • Commercial Water Softeners
      • Pre-Commission Cleaning
      • Tank Reline & Repair
      • TMV Servicing
      • Water Chlorination & Disinfection
      • Water Leak Detection
      • Water Testing
        • Drinking Water Testing
        • Metals Testing
        • Pool Water Testing
        • BSRIA Closed System Testing
        • SDI Testing & Analysis
        • Trade Effluent Testing
    • Training
      • Water Treatment Training
      • Basic Chemistry of Water
      • Industrial Treatment
      • Pre-Treatment
      • Boiler Treatment
      • Cooling Systems
      • Closed Systems
      • Wastewater Training
      • Advanced Treatments
      • Training Dates 2021
  • Wastewater
    • Metals Testing
    • Trade Effluent Testing
    • Wastewater Training
  • Air
    • Ductwork Cleaning
    • Indoor Air Quality
    • Local Exhaust Ventilation Testing
    • Mould Testing
  • Energy
  • Legionella
    • Legionella Risk Assessment
    • Legionella Training Courses
      • Legionella Awareness Training
      • Responsible Person Training
      • Water Hygiene Awareness
      • Pseudomonas Training
      • Training Dates 2021
    • Legionella Testing
  • Contact
  • Search
  • Menu Menu
You are here: Home1 / Knowledge2 / Air3 / When Should You Test For Legionella?
When to test for legionella

When Should You Test For Legionella?

When should you test for legionella is one of the key questions which anyone with responsibility for the management and control of health and safety in the workplace, and in particular the delivery of safe water supplies asks. The simple answer would be to do whatever the UK’s safety laws require you to do as a minimum… and here we’ll explain more.

When is legionella testing required?

The safety regulator in this area, the Health and Safety Executive (HSE) set out in their Approved Code of Practice ACOP L8 and health and safety guidance HSG274 publications many aspects for the control of legionella in the workplace, including when legionella testing is required.

The ACOP L8 and guidance documentation are aimed at keeping people safe from the dangers of the potentially fatal condition known as Legionnaires’ disease.

  • Learn more about Legionnaires’ disease

Understanding your obligations to control legionella is essential

However, most people have never read the HSE’s ACOP L8 or HSG274 documents, probably because of their extensive technical detail.

They are not really documents which are designed for the lay person, but should be considered essential reading for those with responsibility for the maintenance and safety of water systems at work.

This could include business owners, landlords, health and safety managers, property and estates managers, the legionella responsible person and the appointed duty holder.

  • Download your copy of the HSE’s ACOP L8

When should you test for legionella?

We’re going to look at the HSE’s key documents highlighting the main issues relating to the requirements for legionella sampling and water testing.

  • Learn more about testing for legionella

One important point to note is that the requirement for testing for legionella doesn’t apply across the board. However, there are a number of circumstances when legionella testing is required and these include:

  • Control Issues

    When there are doubts about how well the legionella control programme is working.

  • Temperature Control

    The recommended water temperatures are not being achieved.

  • Chemicals

    There are potential issues with the concentration of disinfectants used to control biological growth, including legionella.

  • Other Precautions

    Other water safety precautions aren’t working effectively and could put people at risk.

  • High Risk

    The property or facility is designated as “high risk” – this can include healthcare settings such as hospitals, care homes, nursing homes etc. where the people there are already ill or have weakened immune systems.

Other situations where testing for legionella is recommended

The HSE also sets out other examples of situations where testing for legionella is recommended and these include:

  • Chemical Control

    In any operation that introduces a water system where biocides (special disinfectants) are used for treatment and when the water is stored before use.

    The recommendation in this case is for monthly testing to start off.

    Once you have confidence that your water treatment regime for disinfection or cleaning is working properly, only then can you look at reducing the frequency of legionella testing.

  • Out Of Specification

    When you have set limits of tolerance in your water system, and these levels are consistently being breached.

    Look at all aspects of the water system, including temperature and the concentration of disinfectant products.

    As you try to bring the water system back under control, implement more frequent re-testing to make sure any changes implemented are effective.

  • Increased Risk

    In areas which are at a higher risk from the growth and spread of Legionella bacteria, or where the people using the premises are more prone to developing illness, such as healthcare settings, hospitals or residential care homes.

  • Legionnaires Disease

    Where an outbreak of Legionnaires’ disease has already occurred, and the water system is suspected or known to be the culprit.

  • Learn how testing your water for legionella can improve risk management

How, where and when to take legionella water samples

Each water system is different and you will have to look at its design, inherent risks and how it is performing to work out where to take water samples, and how many samples to take.

The key to any legionella sampling programme is to make sure that you are getting a representative sample of all of the water in the system.

… keep your hot water hot, your cold water cold, and keep it clan and moving.

Water samples should be taken from both hot and cold outlets rather than a mix of warm and cold water flowing through a mixer tap.

It’s good practice to label samples clearly with details of the outlet, the date and where they were taken from.

This procedure allows for easy identification once the legionella testing results are available.

Another recommendation is to “flush” the water system when taking samples.

This means taking the first sample immediately after turning the valve, shower or tap on – this is called a pre-flush sample.

Then leave the water running for at least two minutes before taking another sample for comparison – called a post-flush.

Recommendations for legionella testing

There are a range of recommendations about where you should aim to take samples of water for legionella testing and these include:

  • Risk Assessment

    Any areas highlighted as being higer risk in your legionella risk assessment.

  • Water Temperatures

    Any areas where water temperatures from the hot water feed are below 50 °C (55 °C in healthcare settings), or where the cold water feed temperatures are above 20 °C.

  • Out of Specification

    Locations where levels of disinfectant used to treat the water are lower than your target specification.

  • Low Flow or Stagnation

    Areas of the system where the water is not used often or is prone to stagnation.

    This includes over-sized water storage tanks, areas of low flow, dead-ends and dead-legs in the pipework.

The dangers caused by dead-legs, dead-ends and stagnation

Dead-legs are sections of pipework which have no outlet – they have been islated for some reason or other.

This could be because there was previously a tap or shower which has been removed, but where the old pipe remains connected to the water system.

Many experts also label taps or pipes which are only used very occasionally as dead-legs or little used outlets.

These dead leg pipes and little used outlets allow water to pool and stagnate.

This can increase the legionella risks as the stagnant conditions provide the ideal environment for microbial growth.

Controlling legionella using water temperature – thermal control

Legionella bacteria thrives in temperatures between 20 °C and 45 °C.

This is why the HSE’s guidance recommends keeping hot water above 50 °C ( 55 °C in healthcare), and cold water below 20 °C.

Legionella thrives in temperatures between 20 °C and 45 °C

Put simply, you should keep your hot water hot, your cold water cold, and keep it clean and moving.

More guidance on water sampling

Although every water system is different, there are a few general guidelines to help you work out where to sample water for legionella testing.

Testing cold water for legionella

In cold water systems the sampling points can include:

    • The point of entry (or the nearest outlet) where water comes from a private supply. Take samples here also if the temperature of the water coming from the mains supply is over 20 °C, or is drawn above that temperature from a water storage tank.
    • Both the furthest and nearest outlets on each branch of the system, these are often referred to as sentinel outlets.

Testing for legionella in hot water systems

In hot water systems, samples should be taken at:

    • The outlet at the base of the water heater, as long as the pressure is low enough to allow you to do this.
    • From the furthest and nearest outlets on each branch of the system.
    • From the furthest and nearest point on any loop which water circulates around.

Managing legionella for residential landlords and rental property

It is usually the responsibility of a residential landlord – not the tenant – to manage the potential risks from Legionella bacteria and Legionnaires’ disease in their property.

Under UK safety law it’s a legal requirement for landlords to conduct a legionella risk assessment and to take steps to control any risks identified in that assessment.

If a landlord has an empty property after a tenant leaves, the risk from legionella may increase because the water systems are left unused allowing the water in them to stagnate.

It is essential that landlords should know what to do to stop water stagnating in their water systems.

In general terms, this means making sure that the hot and cold water is flushed at least once a week to keep the water flowing and to stop any risk of stagnation.

If a landlord knows that their property is going to be unoccupied for longer periods, they could think about draining the water systems or paying someone to go in and flush through the system regularly.

This regular flushing will help to keep legionella in check.

What about Legionnaires’ disease at home?

When it comes to privately owned domestic or residential properties, there are no legal requirement to manage or test for legionella.

However, that doesn’t mean that home owners should ignore the risks from legionella entirely.

  • Learn more about legionella testing

There is lots of help and advice available for homeowners who wish to understand more about Legionnaires’ disease and water testing.

Expert legionella testing and risk management solutions

Water Treatment Services offer a range of legionella testing and water safety risk management solutions to support businesses and those responsible for the safety of engineered water systems in the workplace.

Our water safety experts can help you manage your water systems, maintain regulatory compliance and so keep people safe.

With offices in London serving the South and South East England, Manchester (North West), Birmingham (Midlands), Bristol (South East England and Wales), Leeds (North and North East) and Glasgow (Scotland), supported by regional teams of specially trained technicians and engineers we can offer specialist legionella risk assessments, training, water testing and other risk management solutions to businesses throughout the UK and Internationally.

Contact us today to learn how our expert legionella safety solutions can help you.

Contact Us Today

Further reading…

More information about our specialist water safety solutions

Tags: Legionella testing, legionnaires disease, Water testing, water treatment
You might also like
Types of cooling tower All About Cooling Towers
Chlorination of water systems Chlorination of Water Systems, Mains Water Pipework & Water Tanks
Role of the responsible person for legionella control Taking on the Role of the Responsible Person for Legionella Control
Seawater purification Guide to Seawater Purification
Side stream filtration to improve closed systems performance Side Stream Filtration to Improve Closed System Performance
Rainwater harvesting systems guide Guide to Rainwater Harvesting Systems
Testing aerobic colony counts in water Testing Total Aerobic Colony Counts in Water
Limescale, scale and hard water deposits Limescale, Scale Problems & Hard Water Deposits

Search…

What’s New

  • How to Prevent Mould Growth in the Workplace

    How to Prevent Mould Growth in the Workplace

    In this workplace safety review the environmental hygiene specialists …
  • How Expert Reports Help Resolve Disputes

    How Expert Reports Help Resolve Disputes

    Water Treatment Services experienced expert witnesses provide independent, impartial …
  • How Industrial Wastewater Treatment Works

    How Industrial Wastewater Treatment Works

    In this article the wastewater treatment specialists at WTS …
  • Mining Wastewater Treatment & Water Reuse

    Mining Wastewater Treatment & Water Reuse

    In this article the industrial water treatment specialists at …
  • Can Regular Flushing Control Legionella in Hot & Cold Water Systems?

    Can Regular Flushing Control Legionella in Hot & Cold Water Systems?

    In this article the legionella and water safety specialists …
  • What is Coagulation in Wastewater Treatment?

    What is Coagulation in Wastewater Treatment?

    In this article the industrial water specialists at Water …

REVIEWS

4.8
Rated 4.8 out of 5
Water Treatment Services is rated 4.8 out of 5 stars (based on 97 reviews)
Read our reviews

Free Newsletter

Receive exciting features, news, latest research and special offers! Just add your email address and we'll do the rest.

Contact us

Water Treatment Services

[email protected]

Tel: 0330 223 31 31

© Copyright 2022 - EDG Ltd. Operating as Water Treatment Services
  • Twitter
  • Facebook
  • LinkedIn
  • Mail
  • Home
  • About
  • Careers
  • Privacy
  • Environment
  • Reviews
  • Sitemap
Closed System Filters – Equipment Selection Guide Closed system filters - equipment selection guide Creating healthy work environments How to Create a Healthy Work Environment
Scroll to top

WTS response to Covid-19. As a responsible organisation we have robust Business Continuity Plans in place to ensure business as usual whatever the circumstance. In response to Covid-19, our aim is to ensure continued operations whilst protecting both our people and our clients. To this end we have initiated a number of practical measures that will allow us to continue to support our clients in the most appropriate way. Rest assured that we are making every effort to prevent or minimise any impact on our services during this public health challenge.

OK

Cookie and Privacy Settings



How we use cookies

We may request cookies to be set on your device. We use cookies to let us know when you visit our websites, how you interact with us, to enrich your user experience, and to customize your relationship with our website.

Click on the different category headings to find out more. You can also change some of your preferences. Note that blocking some types of cookies may impact your experience on our websites and the services we are able to offer.

Essential Website Cookies

These cookies are strictly necessary to provide you with services available through our website and to use some of its features.

Because these cookies are strictly necessary to deliver the website, refuseing them will have impact how our site functions. You always can block or delete cookies by changing your browser settings and force blocking all cookies on this website. But this will always prompt you to accept/refuse cookies when revisiting our site.

We fully respect if you want to refuse cookies but to avoid asking you again and again kindly allow us to store a cookie for that. You are free to opt out any time or opt in for other cookies to get a better experience. If you refuse cookies we will remove all set cookies in our domain.

We provide you with a list of stored cookies on your computer in our domain so you can check what we stored. Due to security reasons we are not able to show or modify cookies from other domains. You can check these in your browser security settings.

Google Analytics Cookies

These cookies collect information that is used either in aggregate form to help us understand how our website is being used or how effective our marketing campaigns are, or to help us customize our website and application for you in order to enhance your experience.

If you do not want that we track your visit to our site you can disable tracking in your browser here:

Other external services

We also use different external services like Google Webfonts, Google Maps, and external Video providers. Since these providers may collect personal data like your IP address we allow you to block them here. Please be aware that this might heavily reduce the functionality and appearance of our site. Changes will take effect once you reload the page.

Google Webfont Settings:

Google Map Settings:

Google reCaptcha Settings:

Vimeo and Youtube video embeds:

Other cookies

The following cookies are also needed - You can choose if you want to allow them:

Privacy Policy

You can read about our cookies and privacy settings in detail on our Privacy Policy Page.

Privacy
Accept settingsHide notification only