Legionella risk assessment — London
Legionella Risk Assessment London
Landlords have a legal duty under the Health and Safety at Work etc. Act 1974 and the COSHH Regulations to assess and control the risk of Legionella bacteria in a property's water system, following HSE guidance ACOP L8 and HSG274. This is a written risk assessment, not a paid-for annual certificate — for most straightforward domestic lets a proportionate assessment is all that is required, reviewed periodically rather than repeated every year regardless of need.
1974
Year the Health and Safety at Work etc. Act established the landlord's duty of care
60°C+
Recommended hot water cylinder storage temperature to inhibit Legionella growth
Below 20°C
Recommended maximum stored cold water temperature
Unlimited
Maximum fine a court can impose for a serious health and safety breach
On this page
What the law actually requires landlords to do about Legionella
The legal duty does not come from a specific "Legionella law" but from general health and safety legislation. Section 3 of the Health and Safety at Work etc. Act 1974 requires anyone in control of premises to conduct their operations so that people not in their employment — including tenants — are not exposed to health and safety risks. The Control of Substances Hazardous to Health (COSHH) Regulations then treat Legionella bacteria as a hazardous substance requiring a suitable and sufficient risk assessment. The Health and Safety Executive's Approved Code of Practice L8, together with its technical guidance HSG274, sets out how landlords and those managing rented property are expected to meet that duty in practice.
Crucially, what the law requires is a risk assessment, not a certificate. A risk assessment identifies the water system, evaluates where conditions favouring bacterial growth could exist — stagnant water, the wrong temperatures, sediment or biofilm — and records what control measures, if any, are needed. A number of contractors market an annual "Legionella certificate" as if it were a statutory requirement in the same way a Gas Safety Certificate is; it is not. HSE guidance does not set a fixed statutory renewal period for domestic assessments. Instead, the assessment should be reviewed when circumstances change — a new tenancy, an extended void period, alterations to the plumbing — or after a sensible interval if nothing has changed, which for a straightforward domestic property is often every two years rather than every twelve months.
London's housing stock brings some specific risk factors into play more often than newer housing elsewhere. Victorian and Edwardian conversions frequently still have a cold water storage tank or cistern in the loft, which can sit at higher risk if poorly insulated, rarely inspected, or positioned near a warm roof space. Ex-local authority blocks and some purpose-built flats share risers or communal water systems, which brings the freeholder or managing agent's duty into play alongside the individual landlord's. HMOs and student lets with several bathrooms, some of which see very little use between tenancies, are another recurring pattern — a shower that is barely used is exactly the low-flow, stagnant-water scenario the assessment is designed to catch.
Scope of work
What a Legionella risk assessment covers
A proportionate domestic assessment does not require intrusive testing or laboratory sampling in the vast majority of cases. It is a systematic look at the water system and how it is used.
Water system survey and schematic
We identify every part of the property's hot and cold water system — mains supply, storage tanks or cisterns, hot water cylinder, pipework runs and every outlet — and record how the system is configured, since a combi boiler with no stored water presents a very different risk profile to a system with a loft tank and cylinder.
Temperature checks at representative outlets
We check that cold water is being delivered and, where applicable, stored below 20°C, and that hot water is stored at 60°C or above and reaches at least 50°C at outlets within a reasonable running time — the temperature range in which Legionella bacteria are least likely to multiply.
Assessment of tanks, cisterns and cylinders
Where the property has a cold water storage tank or cylinder, we check its condition, insulation, lid fit and accessibility for future inspection, since an open or poorly insulated tank is one of the more common findings in older London properties.
Identification of low-use and dead-leg outlets
Showers, taps and outlets that are used infrequently — a guest bathroom, an unused utility tap, a shower in an HMO room let to a tenant who has moved out — are specifically flagged, since stagnant water sitting in pipework is one of the main conditions the assessment looks for.
Written risk assessment report
A dated, written report recording what was found, the risk rating for the property, and any recommended control measures. This is the document that demonstrates compliance with the duty under COSHH and ACOP L8 — it is kept on file, not renewed automatically on a fixed annual cycle.
Guidance on ongoing landlord monitoring
Simple, low-cost measures the landlord or managing agent can carry out between formal reviews — running taps and showers for a couple of minutes at the start of a new tenancy or after a void period, and noting anything unusual about water clarity, smell or pressure.
When to act
When a Legionella risk assessment applies, and what we typically find
The duty applies to essentially all rented residential property, but certain situations raise the priority and the likelihood of finding something that needs attention.
Any residential letting
Who needs this: the baseline duty to assess and manage Legionella risk applies to any landlord letting residential property, regardless of size or system type. For a simple flat with a combi boiler and no stored water, the assessment itself is usually quick and the conclusion is typically low risk with minimal ongoing action.
New tenancy or change of managing agent
When it applies: taking on a new letting, or a change of managing agent, is a natural point to confirm whether an assessment already exists and is still representative of the property, rather than assuming a previous agent or owner carried one out.
Property left empty for an extended period
When it applies: a void period of several weeks or more allows water in the system to stagnate, which is exactly the condition that favours bacterial growth. Running the system through before re-letting, and reviewing the assessment if the void was lengthy, is good practice.
Older properties with a loft cold water tank
What's commonly found: tanks with missing or ill-fitting lids, insufficient insulation, or positioned close to warm roof spaces. These are straightforward to remedy once identified, but are easy to miss without a dedicated inspection since the tank is rarely looked at once installed.
HMOs and student lets with multiple bathrooms
What's commonly found: one or two ensuite showers used far less than the others, particularly where room occupancy changes through the year. These low-use outlets are consistently the most common finding requiring a simple flushing regime as a control measure.
Blocks of flats with communal water systems
Who needs this: where a building has a shared riser, communal tank or cylinder, the freeholder or managing agent typically holds a duty for the communal system alongside the individual landlord's duty for their own flat, and the two should be checked separately rather than assumed to be covered by one or the other.
How it works
How we carry out a Legionella risk assessment, step by step
The process is proportionate to the property — a straightforward flat with a combi boiler takes considerably less time than a period conversion with a loft tank and multiple bathrooms.
01
Initial information gathering
We confirm the property type, water system type (combi, stored hot water, communal supply), number of bathrooms and outlets, and relevant tenancy details such as occupancy pattern and any recent void periods, before attending site.
02
Site inspection of the water system
We physically trace the hot and cold water system from the point of entry through to every outlet, noting tanks, cylinders, pipe runs and any sections that look unused, altered, or difficult to access.
03
Temperature and visual checks
We measure temperatures at representative hot and cold outlets, check the condition of any storage tanks or cylinders, and note the visual condition of the water (clarity, any discolouration, sediment) where relevant.
04
Risk scoring against HSE criteria
Findings are assessed against the risk factors set out in ACOP L8 and HSG274 — temperature, stagnation, system complexity and materials — to arrive at an overall risk rating for the property, rather than a generic pass/fail.
05
Written report with recommendations
You receive a dated written report setting out what was found, the risk rating, and any specific, proportionate control measures needed — which for most simple domestic lets is limited or none beyond routine good practice.
06
Review schedule recommendation
Rather than an automatic annual renewal, we recommend a review interval suited to the property's actual risk profile, and flag the specific circumstances (new tenancy, extended void, plumbing alterations) that should trigger an earlier review regardless of that schedule.
Buyer guide
How to avoid Legionella assessment scams and overcharging
Because there is no single mandatory licensing body for Legionella risk assessors in the way there is for gas engineers, this is an area where landlords are sometimes sold more than the law actually requires. These checks help you tell a genuine assessment from an upsell.
Understand it is a risk assessment, not a certificate
If a provider talks exclusively about an annual "Legionella certificate" in the same breath as a Gas Safety Certificate, be cautious — the legal requirement is a documented risk assessment reviewed at a sensible interval, not a certificate renewed automatically every year regardless of the property's actual risk profile.
Ask about the assessor's training, not just a logo
There is no single mandatory accreditation scheme for domestic Legionella assessors, so ask directly what training or qualification the assessor holds (such as a recognised water hygiene or Legionella awareness course) rather than relying on a scheme badge that may not mean what it appears to.
Insist on a written report, not just a sticker or a stamp
A proper assessment produces a dated report describing the system, the findings, and the risk rating. A visit that ends with only a compliance sticker on the boiler and no accompanying document has not delivered what the law actually requires you to hold on file.
Be sceptical of mandatory annual re-assessment claims
Some providers imply that failing to repeat the assessment every twelve months is itself a compliance breach. HSE guidance does not set that fixed interval for domestic properties — a longer interval is defensible where the risk assessment concluded low risk and nothing about the property or tenancy has changed.
Combine with a gas safety or EICR visit
Because a Legionella assessment does not usually need a dedicated specialist visit for a simple domestic system, it can often be carried out alongside a gas safety check or electrical inspection on the same call-out, reducing the total cost compared with booking it as a separate appointment.
Query the cost of any recommended control measures
If the assessment recommends work — insulating a tank, fitting a thermostatic mixing valve, replacing a section of dead-leg pipework — ask for that work to be quoted and itemised separately from the assessment fee, so you can judge whether the price is proportionate to what is actually needed.
2025 pricing
Legionella risk assessment costs in London (2025)
The following are indicative 2025 London price ranges. A simple flat with a combi boiler and no stored water sits at the lower end; a period conversion with a loft tank, cylinder and several outlets sits at the higher end.
| Job | Detail | Price range (2025) |
|---|---|---|
| Legionella risk assessment (flat, combi boiler) | No stored water, straightforward system | £90 – £150 |
| Legionella risk assessment (house, stored hot water) | Cylinder and standard pipework | £120 – £220 |
| Legionella risk assessment (period property, loft tank) | Cold water storage tank included | £150 – £280 |
| Legionella risk assessment (HMO, multiple bathrooms) | Several outlets, shared facilities | £180 – £320 |
| Cold water tank insulation or lid repair | Where recommended by the assessment | £80 – £180 |
| Thermostatic mixing valve fitting | Where recommended for temperature control | £120 – £220 |
A Legionella risk assessment is frequently booked alongside a gas safety visit or an EICR to avoid paying for a separate call-out, since the assessment itself rarely needs a dedicated appointment for a straightforward domestic property. Any remedial work the assessment recommends is quoted separately, after the report, rather than assumed as part of the assessment fee.
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Legionella Risk Assessment London — get a clear quote
Tell us about the property and the job. A qualified engineer confirms the scope, agrees a price before work starts, and issues the correct certificate on completion. All 33 London boroughs covered.
Common questions
Legionella Risk Assessment London: frequently asked
Do landlords legally need a Legionella risk assessment?
Yes, in the sense that landlords have a general legal duty under the Health and Safety at Work etc. Act 1974 and the COSHH Regulations to assess and manage the risk of Legionella bacteria in a property's water system, following HSE guidance ACOP L8 and HSG274. There is, however, no separate law requiring a specific document called a "Legionella certificate" the way there is for gas appliances. The duty is met by carrying out a suitable and sufficient risk assessment and acting on any control measures it identifies, which for most simple domestic lets is a straightforward and proportionate process.
Is a Legionella risk assessment the same as a certificate?
No, and this is one of the most common points of confusion for landlords. A risk assessment is a written evaluation of the property's water system that concludes with a risk rating and any recommended actions; it is not a fixed-term certificate that must be renewed on a set annual schedule by law. Some providers market their service as an annual certificate to mirror gas safety terminology, but the legal requirement is the underlying assessment and its periodic review, not a certificate renewed automatically regardless of whether anything has changed.
How often should a Legionella risk assessment be reviewed?
HSE guidance does not set a fixed statutory renewal period for domestic properties. The sensible approach is to review the assessment when something changes — a new tenancy, an extended void period, alterations to the plumbing or heating system — or after a reasonable interval if nothing has changed, which for a low-risk domestic property is often around every two years. A property assessed as low risk with a straightforward combi boiler system does not need annual re-assessment purely as a matter of routine.
Does a small flat with a combi boiler need an assessment?
Yes, the duty still applies, but the assessment itself is typically quick and the risk rating is usually low, since a combi boiler heats water on demand and does not store it in a tank or cylinder where stagnation and temperature issues commonly arise. Landlords should not assume a simple system means no duty at all — it means a shorter, lower-cost assessment, not an exemption from having one.
What is ACOP L8 and HSG274?
ACOP L8 is the Health and Safety Executive's Approved Code of Practice on the control of Legionella bacteria in water systems, setting out what dutyholders are expected to do to comply with health and safety law. HSG274 is the accompanying technical guidance, published in parts covering different types of water system, including the guidance most relevant to evaporative cooling systems, hot and cold water systems, and other risk systems. Together they are the reference documents a competent assessor works to when carrying out a domestic risk assessment.
Who is responsible for Legionella risk in a block of flats?
Where a building has a shared or communal water system — a communal tank, cylinder or riser serving multiple flats — the freeholder or managing agent typically holds responsibility for that communal system, while the individual landlord retains responsibility for the water system within their own let flat. It is worth confirming which party has actually carried out an assessment for the communal parts, rather than each individual landlord assuming someone else has covered it.
What happens if I do not carry out a Legionella risk assessment?
Failing to meet the duty to assess and manage Legionella risk is a breach of health and safety law, and in the event of an outbreak or an HSE investigation, the absence of any risk assessment is likely to be treated as an aggravating factor. Penalties for serious health and safety breaches can include an unlimited fine, and in the most serious cases involving death or serious injury, prosecution can extend to manslaughter charges. For the vast majority of landlords, the practical risk is low, but that is precisely why having a documented assessment on file, rather than none at all, matters.
Can the assessment be combined with other landlord compliance visits?
Yes. Because a domestic Legionella risk assessment does not typically require specialist equipment or a lengthy separate visit, it is commonly scheduled alongside a gas safety check, an EICR, or an HMO compliance visit. This reduces the number of separate call-out fees a landlord pays across a year, and keeps the review dates for different certificates aligned rather than scattered across the calendar.