What Actually Happens During a Legionella Risk Assessment?

It’s more than just turning on a few taps.

When people hear Legionella risk assessment, it can be easy to imagine someone simply turning on a few taps, checking the water temperature and leaving.

Temperature checks are an important part of an assessment, but they are only one part of the process.

A Legionella risk assessment looks at how the property's hot and cold water system is arranged, how it is used, where water may be able to stagnate and whether there are features of the system that could increase risk.

To show what that means in practice, here are some example pages from a recent Thorn Legionella Risk Assessment.

What are we actually looking for?

The assessment considers the water supply, water generation and storage, accessible pipework and fittings, outlets, showers and spray outlets, little-used outlets and identifiable areas where water could stagnate.

First, understand the water system

Before individual risks can be considered, the assessor needs to understand how the property's water system works.

That includes how cold water enters the property, how hot water is produced or stored, whether water storage tanks are present, what rooms and outlets are served and whether there are any obvious features of the system that require closer attention.

Example assessment page showing the scope of the inspection and an overview of the property's hot and cold water system.

In this example, the property has a pressurised system. Cold water is supplied directly from the mains, while hot water is stored in an unvented cylinder. The report also records the rooms and outlets served by the system.

Little-used outlets can matter

One of the things a risk assessment considers is how the water system is actually being used.

An outlet that looks perfectly normal may still require attention if it is rarely used, because water can remain within the pipework, hose or fitting for extended periods.

During this assessment, a shower in the guest WC/shower room was identified as being used less than once per week.

The little-used guest shower was recorded as a low-level risk, with a recommendation for regular flushing while minimising aerosol production.

Importantly, the assessment doesn't simply record that an issue exists. A risk level is assigned and a practical recommendation is provided so the landlord, managing agent or occupier knows what action should be taken.

We're also looking beyond taps and showers

Legionella risk can also be influenced by the design and condition of the water system itself.

In this example, an unused pipe connection was identified in the utility room. This redundant section of pipework could create an area where water is able to stagnate.

Redundant pipework identified during the assessment. The report records the issue, gives it a risk rating and provides a recommended action.

The recommendation in this case is that, if the pipework is no longer required, the redundant branch should be removed back as close as practicable to the live supply to minimise water stagnation.

A record of how the system is laid out

Another important part of the report is the schematic drawing of the water system.

This provides a clear visual record of how hot and cold water travels around the property and shows the principal outlets and components that were considered during the assessment.

Example water-system schematic included as part of the Legionella Risk Assessment report. Blue represents cold water and red represents hot water.

In this property, the schematic records the incoming mains supply, hot-water cylinder, boiler, sinks, bath, showers, toilets, dishwasher and outside tap. It also shows the redundant pipework identified during the assessment.

So, is a Legionella assessment just a temperature check?

No.

Hot and cold water temperatures are measured because temperature is an important part of controlling Legionella risk. But those readings need to be considered alongside the way the complete water system is designed, maintained and used.

A professional assessment brings that information together into a documented report, identifies relevant risks and provides practical recommendations where action is required.

A Thorn Legionella Risk Assessment can include:

Assessment of the accessible hot and cold water system, water temperature checks, hot and cold water storage considerations, little-used and unused outlets, showers and spray outlets, identifiable stagnation risks and redundant pipework, property occupancy considerations, risk ratings and recommendations, a schematic drawing of the water system and a documented assessment report.

Not sure what your property needs? Ask Wendy

Wendy can help you understand the requirements for your property, answer questions about Legionella Risk Assessments and guide you through the information needed before arranging an assessment.

She can also help if you're considering PAT testing, Legionella, or arranging both services together.

Ask Wendy

Legionella Risk Assessments for landlords and letting agents

Thorn provides Elmhurst-approved Legionella Risk Assessments for landlords, letting agents and property managers across Glasgow and East Dunbartonshire.

Legionella assessments can also be arranged alongside PAT testing where both services are required at the same property.

Need a Legionella Risk Assessment?

Find out more about Thorn's Legionella Risk Assessment service and what is involved.

Legionella Risk Assessments