Hi Jay

Wondering why you think that a legionella TESTING regime should be necessary.

The word "legionella" only came into common use about 50 years ago, but has resulted in a pocket industry of businesses selling services on the basis of what in most settings should be an extremely remote risk.

For a construction site in the middle of nowhere, you might be dependent on a "Private Water Supply" in which case there are plenty of nasties other than legionella I would be much more concerned about.

However, if you have a mains supply then you should be able to manage the risks of legionella via the application of fairly basic principles of building services design.

So, cold water below 20 degreees C.

Hot water above 50 degrees C.

No dead ends where cold water can warm up, or hot water can cool down.

What do the engineers say?

This sounds very like overkill to me. Any welfare facility is surely going to be in pretty frequent use, so likely no need for flushing.

Legionella, as I am sure you know, is transmitted through aspiration via breathing in small droplets - will there be a shower as part of the welfare unit?

Originally Posted by: Jay 1979

The resulting bun fight will be who pays for it as it's my understanding that any routine testing/flushing etc must be carried out be a water hygiene competent person.

Ah yes back to that perennial "competent".

At one company our "competent" was the receptionist who weekly would run taps and showers and tick the list in evidence of its completion which would be duly filed in the site service register provided by the company who conducted actual testing.

Working on the assumption it is a well designed facility then there should be no dead legs (these occur over time as a business route and re-routes its supply services e.g. closing canteen operations).

So that leaves the question of flushing the system which as WatsonD has indicated is unlikely to be required given the probable high usage.

As an alternative give the cleaners some training and an extra half hours pay to tick the checklist once a week.

Jay, I live in an 1880 house which was converted into four flats in the 1960s so you can imagine that the paperwork isn't particularly comprehensive as to quite how the water services work.

I'm old school so I like a bath in the morning, but there is a shower upstairs which is used once in the proverbial Blue Moon.

Which DOES mean that there's some pipework and possiblly the odd dead leg, where the water could sit around in the temperature range at which legionella would flourish IF there was any to start with and if there is any viable legionella in your mains water, then there is a public health issue that needs addressing for a lot of customers of your Water Company - and if there is legionella, what else - things like cryptosporidium which probably poses a much greater threat - but which is not on the radar for those selling Legionella services!!

So, when that shower is going to be used it gets a long flush first. 

HSE guidance including the Approved Code of Practice L8 is mostly aimed at situations which MIGHT be relatively high risk, so places with lots of vulnerable people (e.g. hospitals and care homes) and/or places where parts of the system are not in regular use.

So, as an example of the latter. Imagine a hotel with 100 bedrooms but typical 50% utilisation. In quiet times those running the establishment will probably give those booking a room upgrade, the result of which is that some rooms end up being used on a daily basis, but others may be empty for weeks or months at a time. So in the busy periods when the hotel is almost full, this means that some guests are using showers that have been unused for a significant period - the hotelier can't reasonably expect the guests to flush the shower for say 5 minutes before going in and getting lots of water complete with an aerosol which might come complete with a does of legionella.

I still think that your scenario is one for the engineers to sort out and if they know what they are up to, then I can't see why a legionella testing regime is likely to be appropriate, other than to swell the coffers of some testers.

There are times that you want your employer (or, if you are a Consultant, your Client) to spend money and they sometimes do this reluctantly. So, you win no friends by asking them to spend money on things that are unlikely to be anything other than OTT.

Edited by user 14 July 2025 15:51:01(UTC)  | Reason: Typo