Care home hot water: balancing legionella control and scald risk

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A care home is a business with two hot water hazards that pull in opposite directions. To control legionella, HSE expects hot water to be stored at 60°C or above and distributed at 50°C or above. To protect residents from scalds, HSE says water used for whole-body bathing by vulnerable people must not exceed 44°C. The plant room has to make water hot enough to keep bacteria under control, and the bath and shower outlets have to deliver it cool enough to be safe. This guide explains how HSE expects care home owners, managers and maintenance teams to balance the two, where thermostatic mixing valves (TMVs) fit, what staff can check and log, and what needs a competent person. It is based on HSE's health and social care guidance, information sheet HSIS6 and Part 2 of HSG274.

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A note on regulators: HSE says that if you are a provider registered with the Care Quality Commission (CQC) and your premises are in England, CQC is the relevant regulatory body for patient safety matters. The HSE guidance below still sets out how the risks are controlled.

Why care homes face both risks at once

Legionella. HSE says legionella bacteria multiply where temperatures are between 20 and 45°C and nutrients are available, are dormant below 20°C and do not survive above 60°C. It adds that if you run a care home, you are likely to have residents at higher risk of contracting Legionnaires' disease, which can be caught by breathing in tiny water droplets, for example from showers and taps.

Scalding. HSE says health and social care settings have higher water temperatures for reasons including hot water demand, efficient running of the boiler and legionella control, and that temperatures over 44°C can create a scalding risk to vulnerable people. Those at risk include older people, people with reduced mental capacity, mobility or sensory impairment, and people who cannot react quickly enough to prevent injury. HSE notes that many scalding accidents have been fatal and have mainly happened during bathing or showering.

Hot surfaces. HSE's information sheet HSIS6 says contact with surfaces above 43°C can lead to serious injury, often because someone has fallen and cannot move away. That brings radiators and exposed heating pipework into the same risk assessment.

HSE's message is that the two controls must work together: "Any precautions taken should not introduce other risks, for example from legionella bacteria."

The temperatures in one place

These figures come from HSE's health and social care pages, its hot and cold water guidance and HSG274 Part 2. Your own risk assessment sets how they apply to your building.

Where	What HSE says
Hot water storage (calorifiers and water heaters)	60°C or higher. Outgoing water from calorifiers should be at least 60°C.
Hot water distribution	Reaching 50°C within 1 minute at outlets (55°C in healthcare premises). For care homes, HSE says a local risk assessment will help decide which parts of the healthcare guidance are relevant.
Hot supply to TMVs	At least 50°C within 1 minute of running the water, checked monthly with findings recorded.
Baths and showers used by vulnerable residents	Water for whole-body immersion must not exceed 44°C. Where the scalding risk is significant, a Type 3 TMV must be fitted.
Pipework after a TMV	Pipe runs downstream of TMVs should not exceed 2m.
Cold water	Stored and distributed below 20°C.
Radiators and pipework within reach	Where a vulnerable person could be burned, the surface should not exceed 43°C when the system runs at maximum design output.

Where TMVs fit, and why they need care

HSG274 Part 2 describes TMVs as valves that blend hot and cold water to a temperature that safeguards against scalding, "typically between 38 °C and 46 °C depending on outlet use." It also warns that the blended water downstream of a TMV "may provide an environment in which legionella can multiply". That is why the guidance asks for a comparative assessment of scald risk against legionella risk rather than fitting TMVs everywhere.

Baths and showers first. HSG274 says the most serious scalding risk is whole-body immersion, such as baths and showers, and that TMVs should be fitted at these outlets. Where the risk assessment finds a significant scalding risk, for example very elderly or infirm residents, TMVs at hand washbasins and sinks are also required.
Type 3 where the risk is significant. HSG274 says Type 3 TMVs are pre-set and fail-safe, and should be checked regularly to make sure they fail safe if the cold water supply pressure is interrupted. HSIS6 says Type 3 TMVs should be installed when TMVs are replaced or on new installations.
Close to the outlet. HSG274 says TMVs should be as close to the point of use as possible to minimise the storage of blended water, and that one TMV serving several taps can increase the risk.
Basins. HSE says the risk from basins is much lower because there is no full-body immersion. For most people the scalding risk is minimal where water is delivered up to 50°C at hand washbasins, and a hot water warning notice may be enough. Where a resident is assessed as vulnerable at basins, controls such as TMVs should be in place.
Electric showers. HSE says the potential output temperature of electric showers should be checked under fluctuating pressure and flow, and that where they could exceed 44°C you will need healthcare standard electric showers, unless your assessment shows the risk is adequately controlled by other means.
No short cuts. HSIS6 says locking bathroom doors or removing the hot tap head is not advisable where it stops water being flushed through regularly to control legionella, and may only be acceptable in the short term until thermostatic controls are fitted.

What staff can check and log, and what needs a competent person

HSE says outlet temperatures and TMVs should be monitored and maintained so that the controls are effective. The day-to-day monitoring is usually part of the home's routine. Servicing and adjustment are not.

Task	Who, according to the guidance
Monthly temperature checks at sentinel outlets and at the hot water inlet to TMVs, with findings recorded	Routine monitoring under your risk assessment and written control scheme
Testing outlet temperatures with a thermometer where vulnerable residents bathe or shower	Care staff. HSIS6 calls this widely recognised professional bathing practice and says it provides additional reassurance.
Reporting obvious defects	All staff. HSIS6 says staff should be told to report any obvious defects immediately and to take the facility out of use if necessary.
Weekly flushing of infrequently used outlets	Routine, logged once started. HSG274 says care homes may need more frequent flushing, as the risk assessment indicates.
TMV routine maintenance, including inspecting, cleaning, descaling and disinfecting strainers or filters	Competent persons, following the manufacturer's instructions. HSG274 gives "annually or on a frequency defined by the risk assessment".
TMV in-service performance tests and any re-setting	Competent persons, to the manufacturer's schedule
Faults on boilers, calorifiers and gas water heaters	A Gas Safe registered engineer for gas work

Manufacturers set out their own in-service test schedules. As one example, Pegler Yorkshire's instructions for its PEG402 TMV3/TMV2 valve say the purpose of in-service testing is to "regularly monitor and record the performance" of the valve, because deterioration can show it needs service work. They give tests 6 to 8 weeks and 12 to 15 weeks after commissioning, with later intervals set by the results, and recommend in-service tests "once every 6 months as a minimum". Follow the instructions for the valves actually fitted in your home.

HSIS6 adds that maintenance schedules should take account of local conditions, for example hard water or limescale, and the risk of valve failure. Please don't let staff adjust TMV settings, water heater thermostats or boiler controls to fix a temperature problem. Log the reading, report it, and get a competent person to find the cause.

How often should water temperatures be checked in a care home?

This is the question managers ask us most. HSE does not set one single interval for every outlet. The frequencies below are the ones HSG274 Part 2 and HSIS6 describe for hot and cold water systems and care settings. Your written scheme, based on your own risk assessment, can and often should ask for more.

When	What is checked	Target the reading is judged against
Every time a vulnerable resident bathes or showers	Water temperature at the bath or shower, with a thermometer, before the resident gets in	No higher than 44°C for whole-body bathing
Weekly	Flushing of little-used outlets (empty rooms, spare bathrooms, guest washrooms), logged	Outlet run until the water is at its normal temperature
Monthly	Sentinel outlets: the nearest and furthest taps on each hot and cold loop	Hot at least 50°C within 1 minute; cold below 20°C within 2 minutes
Monthly	Hot water supply to TMVs, where it can be measured	At least 50°C within 1 minute
Monthly	Calorifier or water heater outgoing (flow) and return temperatures	Flow at least 60°C; return at least 50°C
Twice a year, summer and winter	Incoming cold water where it enters the building or the cold water storage	Below 20°C
Annually, on a rotation	A representative sample of other outlets, so every tap is checked over time	As for sentinel outlets
To the manufacturer's schedule	TMV in-service performance tests and servicing, by a competent person	Mixed temperature as set for the outlet, and safe shut-off if the cold fails

Two practical points. First, write the readings down where the next shift can see the trend: a bath outlet that read 41°C, then 42°C, then 43°C over three weeks is telling you something before it fails. Second, use a calibrated thermometer and the same method each time (run time, where the probe is held), so a change in the number is a change in the water and not in how it was measured.

What to do when a reading is out of range

Bath or shower above 44°C: do not use the outlet for bathing. Take it out of use, label it, and tell the person in charge. A TMV that lets water through above its set point needs a competent person to test and service it before the outlet is used again.
Sentinel hot tap under 50°C after 1 minute: record it, re-check the same day, and check the calorifier or water heater flow reading. If the plant is below 60°C, the problem is likely at the plant, not the tap.
Calorifier flow under 60°C, or return under 50°C: this is a heating plant problem. Common causes are a boiler that has locked out or is short-cycling, a time clock that is wrong (for example after the clocks change or a power cut), a failed circulating pump or a stuck valve on the primary side. Call a Gas Safe commercial engineer and log what you did.
Cold tap above 20°C after 2 minutes: often heat pick-up from hot pipes in the same duct or a warm plant room. Tell your water hygiene contractor or responsible person; it is part of the legionella risk assessment, not something to fix by adjusting the heating.
Close the loop: note the action taken, the date the fault was fixed and the first good reading after the repair. An inspector reading your log wants to see that problems were noticed, acted on and confirmed as fixed.

Please never ask staff to turn a calorifier or water heater thermostat down to stop outlets running hot, or up to pass a test. The first weakens legionella control everywhere; the second can push TMVs past their working range. Find the cause instead.

TMVs and legionella: keeping the blended water safe

The water after a TMV sits in the range legionella prefers, so HSE's approach is to keep that blended section as short and as well used as possible. In practice that means: fitting the valve close to the outlet, avoiding one valve feeding several taps, flushing outlets in empty rooms, cleaning and descaling TMV strainers and shower heads as the risk assessment requires, and keeping the hot supply to each valve at 50°C or more so the valve has hot water to blend from. When a room is out of use for a long period, the outlet and its TMV should be on the flushing list, not forgotten.

How the heating plant affects both risks

Where the boilers that heat the building also heat the water through calorifiers, or gas-fired water heaters supply it, a fault in the plant room affects both controls:

Stored water below 60°C. A boiler that is locked out, short of output or on the wrong time schedule, or a faulty gas water heater, can leave stored water below the temperature HSE expects for legionella control.
TMVs need a hot enough supply. HSG274 says that for a TMV to work correctly "there needs to be a minimum temperature differential between the hot and cold water supplies and the mixed water temperature". A weak hot supply is a TMV problem as well as a legionella one.
Weak circulation. HSE says the calorifier flow and return check makes sure the supply and return temperatures on each hot water loop are unchanged, which shows the loop is working as it should.
Hot surfaces. HSIS6 lists low surface temperature heat emitters, moving heat sources out of reach, radiator and pipe covers, and lower flow temperatures as ways to cut burn risk, but says lower flow temperatures should not reduce effectiveness or increase legionella risk. Changes like these are a job for a heating engineer working with your risk assessment.
Pressure safety devices. Where calorifiers and water heaters have relief valves, they must be maintained by a competent engineer to the manufacturer's instructions, and site staff should never adjust or test them. HSE's INDG178 explains that the Pressure Systems Safety Regulations 2000 apply to systems containing a "relevant fluid", which includes pressurised hot water above 110°C and steam at any pressure. Where PSSR applies, the duty holder needs a written scheme of examination. Our guide to water heater pressure relief valve checks covers this.

Regulation 35 of the Gas Safety (Installation and Use) Regulations 1998 requires every employer to ensure that any gas appliance, installation pipework or flue at a place of work under their control "is maintained in a safe condition so as to prevent risk of injury to any person." HSE says that in workplaces such as hospitals, work on gas fittings must be carried out by a Gas Safe registered engineer who is qualified to do the work. Our engineers repair commercial water heaters and calorifiers and the boilers that serve them, and our guide to legionella and hot water temperatures in commercial buildings sets out HSE's routine checks in more detail.

Duty holder checklist for care home owners and managers

HSIS6 lists the Health and Safety at Work etc Act 1974 (section 3), regulation 3 of the Management of Health and Safety at Work Regulations and the Provision and Use of Work Equipment Regulations 1998 as the law that applies to hot water and hot surfaces in health and social care. HSE's legionella guidance for care providers adds a COSHH risk assessment of the hot and cold water systems.

One risk assessment, two risks. HSG274 says that in care homes the risk assessment should consider both the relative risks of legionella and scalding.
Link it to each resident's care assessment. HSIS6 says the premises risk assessment should feed into individual care assessments, for example whether a resident might run a bath unattended, cannot get out safely, or has impaired sensitivity to temperature.
Appoint a responsible person. HSE says employers and people in control of premises must appoint someone competent to take responsibility for controlling legionella risk. Where several people share the job, for example because of shift patterns, everyone must know what they are responsible for.
Keep records. With 5 or more employees, significant findings must be recorded. HSE says records should be kept while current and for at least 2 years after, and monitoring records for at least 5 years.
Train and supervise. HSIS6 says staff who maintain the premises or help vulnerable people should be trained and supervised so they understand the risks and precautions.
Maintain the plant. Book servicing of boilers, calorifiers and gas water heaters with a Gas Safe registered engineer, and keep the service reports with your water hygiene records. HSE's HSG220 guidance on health and safety in care homes covers the wider picture.

Where Fast Commercial Boiler Help fits

Legionella risk assessment, water sampling and TMV maintenance need competent people working to your risk assessment. Our part is the heating and hot water plant. If your monitoring shows a calorifier or water heater not holding 60°C, a weak hot supply to TMVs, a falling return temperature or a boiler that keeps locking out, our Gas Safe registered engineers can find and fix the fault on the boilers, water heaters and controls. We work with care homes as commercial premises, and we service plant on a planned preventive maintenance basis.

Safety note

Under the Gas Safety (Installation and Use) Regulations 1998, gas work must be carried out by a Gas Safe registered engineer, and we apply that rule on every site. Don't attempt DIY work on gas appliances, burners, flues or safety devices. On pressure systems, trained site staff should stick to visual and gauge checks, log the readings and report anything abnormal. Never adjust, cap, plug or test-lift a relief valve yourself.

Talk to a Gas Safe commercial engineer

Fast Commercial Boiler Help is a Gas Safe registered (985448) commercial heating business based at 4 Market Hill, Clare, Sudbury, Suffolk CO10 8NN. Our team of over 10 local engineers covers East Anglia and East London, working on commercial boilers, plant rooms, water heaters, and warm air, radiant and unit heaters. We work on commercial premises only.

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Frequently asked questions

What temperature should hot water be in a care home?

HSE says hot water should be stored at 60°C or above and distributed at 50°C or above to control legionella. Where vulnerable residents bathe or shower and the scalding risk is significant, a Type 3 thermostatic mixing valve must stop water being discharged above 44°C.

Do care homes have to fit TMVs?

Where vulnerable people can get into baths or showers and the scalding risk is considered significant, HSE says a Type 3 TMV must be fitted. HSG274 says the decision should come from a risk assessment that weighs scald risk against legionella risk, because blended water after a TMV can let legionella multiply.

Who should service thermostatic mixing valves?

HSG274 says TMVs need regular routine maintenance by competent persons in accordance with the manufacturer's instructions, including inspecting, cleaning, descaling and disinfecting strainers or filters annually or as the risk assessment decides. Staff should record temperature checks and report defects, not adjust valves.

What is the maximum radiator surface temperature in a care home?

Where a vulnerable person could be burned, HSE says the surface should not exceed 43°C when the system is running at maximum design output. Options include low surface temperature emitters, radiator covers and covering exposed pipework.

Can a boiler fault affect scald and legionella control?

Yes. If the boiler or water heater cannot keep stored water at 60°C, legionella control weakens, and HSG274 says TMVs need a minimum temperature difference between the hot and cold supplies to work correctly. A Gas Safe registered commercial engineer should find the fault.

How often should water temperatures be checked in a care home?

HSE guidance describes checking the bath or shower water temperature each time a vulnerable resident bathes, monthly checks at sentinel outlets, at TMV hot supplies and on calorifier flow and return, twice-yearly checks on the incoming cold water, and an annual rotation through other outlets. Your written scheme, based on your own legionella and scald risk assessment, sets the final frequencies and may ask for more.

What should we do if a bath or shower reads above 44°C?

Take the outlet out of use for bathing, label it and report it. The TMV needs testing and servicing by a competent person before it is used again. Do not try to fix it by turning down the calorifier or water heater thermostat, because that weakens legionella control across the building.

Do TMVs increase the risk of legionella?

They can, because the blended water after a TMV is in the temperature range where legionella can grow. HSE guidance is to fit TMVs as close to the outlet as possible, avoid one valve serving several outlets, keep little-used outlets flushed and maintain the valves, so the scald protection does not create a new legionella risk.

Our calorifier is not reaching 60°C. Is that a water hygiene job or a boiler job?

Usually a heating plant job. A calorifier that cannot hold 60°C often has a boiler, pump, valve or time control problem on the primary side. A Gas Safe registered commercial engineer can find the cause, and your water hygiene contractor can then confirm the readings are back within your written scheme.

Sources and further reading

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General guidance only. This article is general information for commercial premises. It is not a substitute for advice from a competent engineer who has seen your site and equipment, or for the manufacturer's instructions. Duty holders remain responsible for their own legal compliance.