The office is reopening. The Christmas tree is down, the heating is cranking back up, and the first thing your employees will do is fill the kettle or wash their hands. But after a 10-day shutdown, the water in your building’s pipes isn’t the same as when you left it.
At Plumbers 365, we warn all our commercial clients that January is “Legionella Season”. When water sits still (stagnates) in pipes for more than a week, bacteria can multiply rapidly.
As a business owner or facility manager, you have a legal duty to ensure the water is safe. Don’t let the first week back result in staff sickness. Here is your expert guide to compliance and the “Back to Work” flush.
Yes, absolutely, according to plumbing experts at Plumbers 365, under HSE L8 guidelines, any water outlet that hasn’t been used for a week or more must be flushed to remove stagnant water and bacteria. Drainage experts at Plumbers 365 suggest that when you unlock the office doors:
This simple action replaces the old, stagnant water sitting in the pipes with fresh, chlorinated water from the mains.
Legionnaires’ disease is a severe form of pneumonia caused by inhaling tiny droplets of water (aerosols) that are contaminated with Legionella bacteria. The bacteria itself is naturally found in low numbers in sources like rivers and lakes. It enters your building’s water system from the mains supply.
According to drainage experts at Plumbers 365, the problem starts when the water stagnates within your building’s pipes at a favourable temperature. The bacteria multiply rapidly, often within a “biofilm” which is a slimy layer that coats the inside of pipes and tanks. When a tap or shower is then turned on, these bacteria are released in the water spray and can be inhaled.
According to drainage and plumbing experts at Plumbers 365, there is no exact “safe” timeframe, as the risk is dependent on temperature and the condition of the system. However, the Health and Safety Executive (HSE) advises that the risk of Legionella growth increases significantly after any period of inactivity of seven days or more. A typical Christmas shutdown of one to two weeks is a prime risk period that requires management as often seen by drainage experts at Plumbers 365. During this time, the chlorine that was in the water dissipates, removing the protection against bacteria. If the heating has been left on low, warming the pipes in ceiling voids, you have created a perfect incubator for bacteria.
According to drainage experts at Plumbers 365, temperature control is your primary weapon against Legionella. The UK’s Health and Safety guidelines (ACoP L8) are very clear:
Legionella bacteria thrive in the “danger zone” between 20°C and 45°C. Keeping your water outside these temperatures either kills the bacteria (hot) or keeps it dormant (cold).
Plumbers 365 drainage experts suggest that your hot water cylinder (calorifier) should be set to 60°C to pasteurise the water. If your office has turned the boiler down to save money over Xmas, you may have dropped into the danger zone.
Plumbers 365 drainage experts have often seen that as bound under UK health and safety law, every business must appoint a “Responsible Person” with the “Duty Holder” being appointed to a legal role and not just a job title. The Duty Holder/Responsible Person could be:
Under the Health and Safety at Work Act 1974 and COSHH regulations, if you control the premises, you are liable. You cannot simply say “the plumber deals with it.” You must have a named person who ensures the risk assessment is done and the flushing regime is logged. If an outbreak occurs, this is the person the HSE will interview.
Plumbers 365 drainage experts consider a simple flush as a start where the full, safe procedure involves:
According to drainage experts at Plumbers 365, if you have a water system and are an employer or landlord, a Legionella Risk Assessment (LRA) is a legal requirement in the UK. Our experts suggest that you don’t need a complex manual for a small shop with one toilet, but you do need a formal assessment. If you have 5 or more employees, the findings must be written down. It identifies risks (like water tanks, shower heads, or unused pipes) and sets out how you will control them.
According to drainage experts at Plumbers 365, you should look for discoloured water(brown/orange), a “rotten egg” smell, or cold water coming out warm (or vice versa) as the classic signs of stagnating water in a commercial building. Drainage experts at Plumbers 365 suggest for a sensory check where:
However, dangerous water can look and smell perfectly normal. Temperature testing is the only accurate gauge according to plumbing experts at Plumbers 365.
This is a common misconception often posed as a concerning question to our drainage and plumbing experts at Plumbers 365. Standard office air conditioning systems that just recirculate and cool air do not pose a Legionella risk as they do not use water in a way that creates aerosols. The risk comes from systems that use water for cooling, such as evaporative cooling towers or humidifiers since these are rare in typical office environments but are a major risk where they exist.
As often seen by drainage experts at Plumbers 365, the big outbreaks historically come from large industrial cooling towers on roofs that spray water into the air. If you manage a large facility with these, strict monthly testing is mandatory.
A “dead leg” is a length of pipe that has been capped off and is no longer used. It is a perfect incubator for Legionella as water sits in it and stagnates as often observed by drainage experts at Plumbers 365. HSE guidance is clear: dead legs should be identified during a risk assessment and removed as a matter of priority. They serve no purpose and present a significant, unnecessary risk to the entire water system.
Ensuring water safety is not just good practice; it is your legal duty. Returning to work after a shutdown requires more than just unlocking the door. A proactive approach to water management is essential.
Plumbers 365 offers professional water safety services for UK businesses:
Ensure a safe return to work for your team. Contact Plumbers 365 today.
