Reopening a building requires an analytical mind to consider all the factors that need to be addressed. This has been made more complicated by the need to follow Covid-19 guidance on hygiene and social distancing. 

Spencer Culley

Spencer Culley

There may also be businesses desperate to open after so long that they cut a few corners or try to reduce costs by neglecting to use an expert service provider.

When it comes to water system management, this temptation must be ignored. Buildings that have been vacant for even a short time are at risk of Legionella build-up in water systems – and the longer a building has been vacant, the higher the risk.

We have even seen a significant number of Legionella sample failures from buildings where weekly flushing cycles have been undertaken. Flushing alone may not be enough and there can be no room for error. Legionella is already a deadly bacterium and anyone who has recovered from Covid-19 might be especially susceptible to another respiratory infection.

In most cases, full system disinfection (hot and cold) is the most effective way to remove all microbiological hazards that have accumulated within a system during a period of closure. This can be a complex task that requires expert help in order to ensure it is carried out safely and effectively.


The disinfection process involves the introduction of an appropriately selected biocide into specific points across the hot and cold water system, including both mains-fed systems and those supplied by water-storage vessels, and should only be undertaken with a good understanding of the system layout and related water assets. Samples from sentinel taps and other outlets should then be taken between two and seven days after the work is completed and submitted to the laboratory to be analysed for the presence of Legionella bacteria – testing within 48 hours may give false-negative results.

It is a process that may seem simple enough, but the experts that carry out this work are highly experienced. Businesses must engage this experience in order to protect their workforce and customers. Remember the old adage: you pay for the years of experience and not the time it takes to complete the job.

Spencer Culley is director at Churchill Environmental