Legionella Monitoring

Legionella Monitoring | Legionella Control Services

Legionella Monitoring


By law you must take suitable precautions to prevent, manage, and control the risk of exposure to legionella to meet the following regulations. Failure to address these issues not only put your employees and the public at risk but could leave you liable for enforcement action by the HSE Legionella Control Association/ Local Authority Environmental Health Department.
What are your legal requirements?

Duties under The Health & Safety at Work Act 1974 (HSWA) extend to risks from Legionella arising from work activities. In addition, harmful micro-organisms (biological agents) are subject to the Control of Substances Hazardous to Health Regulations 2002 and Amendment 2003 and 2004 (COSHH) and management responsibilities – The Management of Health and Safety at Work Regulations 1999 (MHSWR). A full list of the hierarchy of legal, guidance and British Standard documents are outlined below:

  • The Health and Safety at Work Act (HSAWA)
  • The Management of Health and Safety at Work Regulations (MHSWR)
  • The Control of Substances Hazardous to Health Regulations (COSHH)
  • The Notification of Cooling Towers and Evaporative Condensers Regulations
  • ACoP and Guidance L8
  • HSG 274 Technical Guidance Part 1-3
  • BS 8580-1 Design, Installation, Testing and Maintenance of Services Supplying Water
  • HTM 04-01 Safe Water in Healthcare
  • HTM 01-05 Decontamination in Primary Care Dental Practices
  • HSG 220 Care Homes
  • HSG 282 Spa Pools
  • BS 7592 Sampling for Legionella Bacteria in Water Systems


For more information on your requirements as listed above visit our support page.

How do I meet Legionella Compliance?


Legionella Risk Assessment

The first step in meeting Legionella compliance is to undertake a legionella risk assessment that will identify the potential risks Legionella posed by your water systems.

Legionella Remedial Works

Once these risks have been identified they should be removed, substituted or managed. This means undertaking any remedial works to reduce the risks identified.

Legionella Monitoring

Finally, you will need to control and manage the ongoing risk of Legionella exposure from your water system to employees and visitors by carrying out continued Legionella monitoring.

Legionella monitoring to meet HSE guidelines

Below is a full list of legionella monitoring services that you may need depending on your water system to meet HSE’s Legionella Compliance.

Weekly Flushing

Quarterly Return Loop

Annual Review

Annual CWH Inspection

Annual Water Softener Service

Monthly Temperatures

Six Monthly Expansion Flushing

Annual Tank Inspection

Annual TMV Servicing

Annual Water Testing

Quarterly Descaling

Six Monthly Filter Servicing

Annual Cylinder Inspection

Annual Representative Temp

Other Risk Systems

Why do I need to do water monitoring?


Under the Health and Safety at Work Act 1974 and in compliance with the Approved Code of Practice (ACoP L8, HSG 274), duty holders, including employers and those in control of premises, must ensure the health and safety of their employees or others who may be affected by their undertaking.

This includes taking suitable precautions to prevent, manage and control the risk of exposure to legionella and legionnaires disease. You can do this by undertaking the following control measures: a legionella risk assessment, actioning all identified legionella risks within the simple risk assessment with legionella remedial works, sampling the water quality to confirm bacterial presence with legionella testing, and carrying out ongoing record-keeping also known as legionella monitoring or water monitoring.

Take our online legionella training course for a better understanding of the compliance needed.

When and how often do I need legionella monitoring?


Following a legionella risk assessment, a water logbook should be produced to aid with your legionella monitoring and record keeping. Each water system is different and therefore will require a bespoke water monitoring plan to control legionella levels and any potential exposure to legionnaires disease. Typically tasks should be undertaken weekly, monthly, quarterly, six-monthly and annually.

How much does water monitoring cost?


Water monitoring prices vary depending on the number of water outlets, cold water storage tanks, hot water cylinders, combi boilers and other water assets that may be present. The number of assets within your water system will determine the time spent on-site and how long it will take to carry out all legionella monitoring tasks.

So how much does water monitoring cost? Across the industry, prices vary enormously often depending on the size of the company you use and their processes, speed of work and professionalism.

uRisk carries out price comparisons and reviews regularly to ensure our prices are kept competitive and with the customer in mind.

How long does a water monitoring visit take?


Depending on the type of water monitoring visit it is and the size of the water system will determine how long a water hygiene engineer is on-site. For monthly temperature monitoring, you can expect the engineer to be on-site for a period of 30-60 minutes on average. However, if the tasks are quarterly de-scaling you might expect the engineer to be present for 1-4 hours.

Other tasks such as TMV servicing and inspections can take considerably longer due to the nature of the works.


How long are water monitoring contracts?


Legionella monitoring contracts at uRisk range from 2 to 5 years. In special circumstances we offer 12-month contracts, but the longer the contract the better price we can offer you.

What if I choose not to do legionella monitoring?


It is your legal responsibility under HSE ACOP L8 (HSG 274) to ensure the safety of those at your place of work or property. Should you choose not to undertake water monitoring, you run the risk of allowing harmful bacteria to grow within your water system which may lead to illness and prosecution.


Service process

Get a Quote

To get a quote you can phone, email or complete our ‘Get a Quote!’ form to receive a quotation within 24 hours.

Book an Appointment

Once you’re happy with your quote we’ll confirm a suitable date and estimated time of arrival for your appointment.

Your Appointment

An engineer will be with you on your scheduled date, and will call you prior to arrival (when safe and possible).

Report & Support

Our team will quality assess your report for PDF distribution, typically within 2-10 days of the site visit.

All payments are due prior to booking completion unless agreed in writing for 30 days from the date of invoice. We will hold your booking time for 24 hours whilst we wait for payment.

Legionella Control and Management Tasks Explained

Weekly Flushing

Most taps are used weekly if not daily, which helps to keep water moving to make it difficult for bacteria to settle and grow. However, in commercial settings, many outlets are seldom used if at all. Examples might include office showers, school changing room showers, accessible toilets, and bib taps. Stagnation is arguably the number 1 cause for legionella proliferation, and therefore plays a vital role in your legionella control and management.

All infrequently used outlets should be flushed every 7 days (or twice weekly in healthcare) to ensure water does not stagnate and encourage legionella growth. Outlets should be flushed until a stable and compliant temperature is reached.

Knowing what outlets are infrequently used – there are 2 good indicators to tell us what outlets need to be added to the weekly flushing regime. Number 1 – you know you do not use the outlet. If it’s rarely used or an unoccupied area, it should be put onto the weekly flushing regime. Number 2 – non-compliant temperatures. If your outlet is not reaching the desired temperature range within the allowed timeframe when most other outlets do, this indicates that the outlet may be infrequently used and should be placed onto the weekly flushing regime.

Monthly Temperatures

Temperature plays an important role in legionella bacteria control and management as the legionella bacteria can proliferation between 20-50°C and has even been known to grow at 54°C, with legionella’s most favoured temperature being 37°C (body temperature) which is why it can be dangerous to humans once contracted causing illness such as legionnaires disease, pneumonia, Pontiac fever, and the common cold and flu.

Temperatures must be reached within a specific timeframe. This allows us to ensure temperature testing remains consistent and allows us to determine the frequency of use of the outlet and potential areas of stagnation or risk.

Temperatures are required to be taken from all heat sources and the sentinel points of a water system. Sentinel points are the monthly temperature points at the nearest and furthest outlets of each water system. For example, taking the sentinel points from a cold-water storage tank would consist of taking temperature from the nearest tap to the tank and the furthest away. For heat sources, this means taking the temperatures nearest and furthest from all heat sources. This may be a cylinder, electric water heater, boiler or otherwise. However, in the case of an instant water heater with a single outlet such as a shower, the outlet becomes the nearest and furthest so one temperature would be all that can be taken.


Temperature timeframes

Hot temperature – 1 minute

Cold temperature – 2 minutes


Temperature guidelines

Hot outlet – 50°C (55°C in healthcare)

Cold outlet – <20°C

TMV* outlet – 38-43°C (ranges vary for showers/baths)

Scalding – 44°C


Heat sources

Cylinder and flow – 60-65°C

Cylinder return – 50°C (55°C in healthcare)

Combination water heater – 60-65°C

Boiler – 50-60°C (55°C minimum in healthcare)

Electric water heater – 50-60°C (55°C minimum in healthcare)

Instant water heater – 50-60°C (55°C minimum in healthcare)

*TMV – thermostatic mixing valve, blends hot and cold to create a reduced, non-scalding temperature. Often required for vulnerable persons and in healthcare.

Quarterly Descaling

Limescale is a great source of nutrients for legionella. Limescale can be found anywhere in a water system where there is hard water. The UK suffers from hard water due to the chalk limestone earth below the ground that finds its way into our reservoirs that supplies our mains water. Therefore, all outlets should be dismantled, cleaned, and descaled to remove the presence of limescale. This includes taps, spray heads, tank cleaning, showerheads and hoses.

Quarterly Re-Circulating Return Loop

Taking the temperature from the re-circulating return loop quarterly for subordinate temperatures.

Six Monthly Expansion Vessel Flushing

An expansion vessel is a small white, blue, grey, or red tank. The white, blue, and grey vessel colours are to identify water system expansion vessels and the red is to identify heating system expansion vessels. Each vessel includes a rubber diaphragm that goes across the middle, where the bottom half of the vessel is filled with water and the top half with pressurised air. When water is heated at the heat source (like a cylinder) it may expand as much as 4%. The expansion vessel allows this expanded water (increase in water size) from the heat source (cylinder) to flow into the expansion vessel where the bottom half of the vessel (water) may push the diaphragm up into the top hair (airside) to allow for the expansion in water.

So why do we need to flush an expansion vessel? Well, there are 2 primary reasons. One the expansion vessel is a dead end, and as such does not allow water out of it and therefore encourages stagnation both inside the vessel and all the pipework leading to it from the feeding tee (branch of pipe that leads to it). Secondly, the diaphragm is made of rubber, which is a great source of nutrients for legionella.

The guidelines outline that we must flush the expansion vessel for six months to remove stagnant water from the vessel and relevant pipework.

Six Monthly Filter Servicing

A filters job is to cleanse the water impurities and allow for good quality water to pass by and therefore provides us with good quality water free from bacteria’s and the like. And in doing so the filter will become dirty itself. You will often see an internal filter that initially looks like a clear white tube that eventually turns brown/black with impurities over time.

Most manufacturers have given this timeframe 6 months before a filter is needed to be replaced or cleaned.

Annual Review

An annual review is an important part of your legionella testing and control. At this stage, your risk assessments, logbook, schematic, and other records will be reviewed by an engineer to confirm the status of your legionella control and management.

Annual Cold Water Storage Tank Inspection

Coldwater storage tanks overall as a design will not change from year to year but the condition of the tank internally certainly can. Coldwater storage tanks are subject to poor temperatures (too hot or freeze), foreign bodies (bugs, animals), sediment (from mains), biofilm (from stagnation), wall spores (bacteria), and so on. Therefore, it is important to inspect both the internal and external conditions of a tank annually as a minimum.

Annual Cylinder Inspection

Hot water cylinders are subject to continual heat changes that may increase the risk of legionella through non-compliant temperatures. They also require temperature gauges, pipe insulation, and should be purged periodically to remove any internal limescale, debris, or sediment. Cylinders are prone to limescale build-up and an inspection and drain down (purge) of the cylinder will help to remove unwanted items within the cylinder.

Annual Combination Water Heater Inspection

A combination water heater consists of a cold-water storage tank on top feeding the hot water cylinder below, hence the name combination water heater. Therefore, both the tank and cylinder inspections and servicing must take place on a combination water heater.

Annual TMV Servicing

TMV or thermostatic mixing valves are blending valves that mix the hot and cold water to reduce the risk of scalding where temperatures are often set to 41°C, 3°C lower than the scalding starting temperature for vulnerable persons at 44°C.

TMVs are fitted with filters that protect the valve, where these filters are prone to blocking with limescale, sediment, and other matter. Therefore, a TMV should be serviced at least annually as recommended by most manufacturers. TMV servicing will often include temperature calibration, failsafe testing, and clean and disinfection of TMV parts amongst other actions where required.

Annual Representative Temperatures

Whilst you are required to undertake monthly temperature monitoring throughout the year at your sentinel points. You are also required to take the representative temperature at other points in the system to gather information on the rest of the water system. This could be made up of 10% of outlets in the system from areas you do not normally take the temperature from when undertaking monthly temperatures.

Annual Water Softener Servicing

Manufacturers recommend that water softeners should be serviced annually. This often includes a regeneration process where backflow is created to remove any bacteria or otherwise within the water softener system. Additionally, a review of the brine (salt) tank and other elements will be reviewed to ensure a safe and suitable working condition.

Annual Water Testing/ Legionella Sampling

It is recommended that legionella sampling or a legionella risk assessment is undertaken periodically or at least annually. The number of samples required will depend entirely on your water system. For example, samples should be taken from dead legs or areas of stagnation, cold water storage tanks, and all sentinel points to provide an accurate overview of the water systems condition.

Annual Water Testing/ Legionella Sampling

There is a range of other risk systems that require more bespoke management. For more information please contact our team. Below we have a list of water systems that commonly require regular legionella risk assessments:

  • Ultrasonic humidifiers/ foggers
  • Spray humidifiers
  • Air washers
  • Emergency showers
  • Sprinkler and hose systems
  • Swimming pools/ whirlpools/ jacuzzis
  • Horticultural misting systems
  • Dental chair
  • Vehicle wash systems
  • Fountains and water features
  • Industrial processing water systems
  • Reverse osmosis
  • Water dispensers
  • Evaporative cooling systems
  • More

Your dedicated water hygiene team

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Legionella Control Services

Luke V

Business Manager

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.

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 Thorne
20:29 07 Aug 18
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 Port
20:41 07 Aug 18
Brilliant Service, efficient, professional, punctual and friendly.
Alex Windsor
Alex Windsor
18:21 15 Jan 19
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 Pond
20:37 07 Aug 18
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 Gohil
12:49 12 Mar 18
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 Pates
18:30 07 Aug 18
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 Maskell
18:02 15 Jun 20
Brilliant service! Thanks a lot for the hard graft
Leon Macauley
Leon Macauley
21:12 15 Jan 19
Extremely happy with our legionella risk assessment carried out by uRisk, easy to understand and great customer service. Thanks again
Nickayla Robertson
Nickayla Robertson
21:22 15 Jan 19

We want to help you comply!