# Do I need a legionella assessment or a water test?

Assess your water system first. An assessment and a water sample answer different questions.

Jurisdiction: England, Wales, Scotland
Source check: 2026-11-03. Editorial status: source-checked draft; specialist sign-off pending.

## Who this covers
Employers and people in control of premises, including landlords, with responsibility for water systems.

## The requirement
Identify and assess sources of legionella risk, prevent or control exposure, manage the risks and keep the appropriate records.

## Practical steps
- Identify your water systems and who is responsible for them.
- Assess the system, its use and anyone particularly vulnerable.
- Put proportionate controls and monitoring in place.

## Common mistake
A water sample does not replace an assessment. HSE says domestic landlords do not need a legionella test certificate; sampling is not usually required for domestic hot and cold water systems.

## Timing
Review the assessment regularly and when the system or its use changes. Controls depend on the assessment.

## Questions for a provider
- Why does our system need the proposed monitoring or sampling?
- Who will manage the controls after the assessment?
- Does the assessment cover periods of low use?

## Official sources
- [HSE: legionella duties](https://www.hse.gov.uk/legionnaires/what-you-must-do/index.htm)
- [HSE: landlords and legionella](https://www.hse.gov.uk/Legionnaires/legionella-landlords-responsibilities.htm)

General information, not an assessment or a statement that a business is compliant.


## Connect the assessment to everyday water-system management

### Before you commission work
Locate existing assessments, system information and monitoring records. Ask the person maintaining the building about changes, unused areas and access restrictions. Tell the provider which tasks are done by staff and which are contracted out so their proposal can identify gaps or duplicated work.

### Follow through on the result
Ask for the report to be explained to the person who will manage the actions. Confirm what happens when a planned task is missed or a finding needs escalation. Keep records accessible when staff or suppliers change. If a recommendation cannot be implemented as described, ask the competent provider to resolve that difficulty instead of silently changing the instruction.

## Related buying guides
- [Legionella risk assessment quotes: assessment, sampling and monitoring](https://whatcompliance.com/buying-guides/legionella-risk-assessment-quotes)

## Buying the right work
- Identify who controls the system and collect existing information.
- Explain periods of low use, stored water and any planned system changes.
- Ask what a proposed sample will tell you and why it is appropriate to this system.

## What you can do yourself
HSE describes a proportionate approach to low-risk domestic rental systems. Some simple systems can be assessed by someone with an adequate understanding; more complex systems may require specialist help.

## When to get help
Use competent advice if the system, its condition or its users make the risk unclear. Do not assume the low-risk domestic examples apply to a workplace cooling tower or a complex healthcare system.

## Records to keep
- The system assessed, responsibilities and significant findings.
- Any control scheme, monitoring and actions relevant to the risk.
- Changes in use, occupancy or system condition that may require review.

## Do domestic landlords need a legionella test certificate?
HSE says there is no such requirement for domestic landlords. They still need to assess and control legionella risks.

## Does a clear water sample mean the risk is managed?
A sample is a result for a point in time. It does not establish whether responsibilities, system management and controls are adequate.

Source check for this expanded guide: 2026-11-03. Specialist sign-off pending.