Legionella Risk After Christmas Brings Increased Risk

The Christmas period creates one of the highest risk windows for Legionella growth. Reduced occupancy, lower water usage, and delayed maintenance all combine to create the perfect conditions for bacteria to develop.

The risk rarely appears during the holidays themselves. It shows up in January, when buildings return to normal use.

Why Legionella Risk Increases Over Christmas

Legionella bacteria thrive in stagnant water. Over Christmas, many buildings experience long periods of low or no use.

Water sits in pipework. Tanks are not refreshed. Temperatures fluctuate as heating systems are turned down or switched off.

In partially closed buildings, only certain outlets are used, leaving others untouched for weeks. This increases the risk of bacterial growth throughout the system.

Types of Premises Most at Risk

Some buildings are more vulnerable than others after the holiday period.

Offices often shut down completely or run on skeleton staff. Schools and education settings close for extended periods. Dental and healthcare premises may operate reduced services. Care homes may experience lower occupancy or changes in routines.

Any building with complex water systems or vulnerable users faces increased risk after prolonged inactivity.

Common Post-Christmas Issues Identified

Legionella Assessors regularly identify the same problems in January.

Outlets failing to reach safe temperatures. Taps and showers that have not been used or flushed. Incomplete or missing flushing records. Routine monitoring tasks missed due to holiday cover or reduced staffing.

These issues are rarely deliberate. They are the result of disruption to normal routines.

What Duty Holders Should Do in January

January is the time to reset control measures.

Water systems should be fully flushed. Hot and cold water temperatures should be checked and recorded. Written schemes should be reviewed to ensure they still reflect how the building is used.

Where systems have been inactive or control measures have lapsed, it may be appropriate to commission water sampling to confirm safety.

Does This Mean You Need a New Legionella Risk Assessment?

Not always.

A Legionella Risk Assessment should be reviewed whenever there has been a change in building use, occupancy, or water system management. If the assessment is still current and control measures were followed, a review may be sufficient.

In higher risk settings, or where records are incomplete, a new assessment or targeted sampling may be recommended by professional Legionella Assessors.

The key is proportional, evidence-based decision making.

Why January Is the Most Important Month

Legionella risk builds quietly. It does not wait for a busy period. The greatest risk often appears immediately after extended downtime.

Acting early in January reduces risk, protects occupants, and demonstrates compliance with health and safety duties.

Professional Legionella Risk Assessments from The HSRA

At The HSRA, our experienced Legionella Assessors support businesses across the UK with Legionella Risk Assessments, reviews, and water sampling.

We provide clear advice, practical recommendations, and documentation that stands up to scrutiny.

If your building was quiet over Christmas, now is the time to act.

Learn more

FAQs – Legionella Risk After Christmas

Why is Legionella more common after the Christmas period?
Reduced water usage and stagnant pipework over the holidays create ideal conditions for Legionella bacteria to grow.

Which buildings are most at risk in January?
Offices, schools, healthcare premises, dental practices, and care homes are commonly affected due to reduced occupancy.

Do I need a new Legionella Risk Assessment after Christmas?
Not always. A review may be enough if the assessment is current and control measures were maintained.

When should water sampling be carried out?
Sampling is usually recommended when systems have been inactive, records are missing, or there is concern about control measures.

Who is responsible for managing Legionella risk?
The duty holder, usually the building owner or managing organisation, is responsible for managing Legionella risk.

What does a Legionella Assessor do?
A Legionella Assessor evaluates water systems, identifies risks, reviews control measures, and provides guidance to ensure compliance.

How can The HSRA help?
The HSRA provides Legionella Risk Assessments, reviews, and water sampling services tailored to your building and usage patterns.