Health and Safety
Compliance - legionella control PDF Print E-mail
Written by Giles Green, 2007   

Giles Green, Principal Scientific Advisor at Bureau Veritas, discusses how intelligent compliance rather than unthinking conformance can be applied in controlling the risk of legionella infection. 

Is there a way of controlling legionella without increasing risk of scalding?

How often should an underused water outlet be flushed?

I don't mind being quoted on this, but I certainly would not advise changing your behaviour: I do not think the law requires you to drive on the left on a single carriageway in Britain. My Highway Code states only that you should (rule 136) but elsewhere it is very clear about other things that you must or must not do and it emphasises these with bold red capital letters, but when it comes to driving on the left, all it says is "should".

So what would happen if I chose not to drive on the left, I wonder. First of all, I could be putting into practice a technique taught to me on an advanced riding course in which road positioning is not decided just on the basis of a custom, but according to the formula Safety, Stability, View. This means that on an apparently clear road, the correct position for approaching a left-hand bend is on the right-hand side of the road... honestly! And this was a proper advanced training course, approved by RoSPA. Apparently, police motorcyclists refer to this as "bouncing off the kerbs" and use it all the time.

But what does this have to do with legionella control, you may be wondering. The point I am trying to make is that there is a difference between compliance and conformance. Compliance is required by law and is not really open to any discretion at all, but conformance can be - indeed arguably should be - set aside on occasions when there may be a better way to comply.

Consider the classic Kingston Controls for cold and hot water systems. In their briefest form, they could be summarised as having four elements: keep the cold water cold, keep the hot water hot, keep the water systems clean and keep the water fresh. These guidelines have been used for over 20 years and have been proven effective, not only in controlling the risk of legionella infection, but even in controlling legionella below detectable limits almost all the time in almost all systems.

The Health and Safety Executive have positively advocated them for many years and few people would argue that they are not the 'right' or the 'correct' way to comply with the legal requirement to control the risk of legionella infection.

But what about scald risk? And what about carbon footprint? And what about water wastage?

In a typical year in Britain, the number of deaths by scalding is not much lower than the number of cases of legionnaires' disease, and legionnaires' disease is typically fatal in only about one in eight cases. Yet we still advocate storing hot water at 60°C and delivering it at about 50°C. And there can be no question that heating water to 60°C takes much more energy than it would to heat it to 40°C - a nice, warm washing temperature. Then there's the "flush under-used outlets" recommendation, which looked rather odd against a background of autumn starting in early August and countryside with more than a hint of scrub about it.

So this is where informed indiscretion comes in: intelligent compliance rather than unthinking conformance.

I know a site where concerns over the risk of scalding vulnerable members of the public led to a decision to operate outside the mainstream of the Kingston Controls and to set the hot water temperature at 45°C. This brought the scald risk under control, but it allowed an avoidable legionella infection risk to develop. Clearly, this was a difficult choice to make and one in which no wholly 'right' answer could be found: raise the water temperature and risk scalding visitors; reduce the water temperature and risk giving them an infection they may not live to remember. So how was this dilemma resolved?

Before the current guidance on legionella control, there were two separate documents, one was the Health and Safety Commission approved code of practice (the ACOP) and the other was guidance from the Health and Safety Executive (known as HS(G)70).

This second document advocated the familiar Kingston Controls, but it also contained a very important additional piece of advice in the event that hot water temperatures could not be maintained and that was weekly thermal disinfection. The line of reasoning seemed to be that some systems were simply not capable of maintaining a control temperature so, rather than insist by means of Improvement Notices, Prohibition Notices or prosecution, the pragmatic solution was to find a reasonably practicable technical fix.

This was something that almost every system could achieve (and for those few that could not, there was always the strong arm of the law) and which controlled the proliferation of legionella, albeit in a fail-unsafe rather than fail-safe way, and this is exactly what the site I referred to does and has proven by targeted legionella testing over a prolonged period. I understand they are now about to embark on an energy audit, which should tell them whether this regime saves energy overall or, with the weekly flush of hot water, uses more. I do not know what the balance will prove to be, but I do know that for a number of years, this site has complied with the requirement to control legionella infection risk, without appearing to conform to the conventional temperature regime.

Which brings us to keeping water fresh by pouring it down the drain and replacing it with some of the dwindling contents of our reservoirs. How often should an underused outlet be flushed? How long should it be flushed?

The usual advice is to flush weekly and the HSE advocate "several minutes", but would that be sufficient for a tap supplied by a large storage vessel? Or would it be a profligate waste of water at a tap at the end of a 2m spur from a well-used main in a cool plant room? And would such profligate waste be a breach of the water fittings regulations that outlaw wasting water? Again, a dilemma; again it is not easy to see how to comply by conforming.

On the other hand, there is a clear legal obligation on those who are responsible for matters of health and safety at work to be competent or to make use of those who are. That is required by law and as such is not open to discretion, so that is where the answer lies: gain the necessary competence, or use the services of someone who already has. It is as easy as that.

So what would a competent individual judge to be enough flushing for an underused outlet to balance the obligation to control legionella risk against the unlawfully wasting water?

This question is in fact more significant in its choice of words than in its answer. The really important words are not (perhaps surprisingly) "competent individual" but "judge" and "enough".

A competent individual can, by considering the information available, appraise the benefits and disadvantages of a situation and do the same with a proposed course of action to reach a judgement that something must, should or ought to be done, or that it is not required. If the judgement is that some action is required, the responsible person can, again by considering the information available, judge what action is likely to be effective, what may not be sufficient and what would be deemed excessive.

This follow-a-formula versus appraise-and-judge debate was recently played out on the matter of whether or not to remove cooling tower fill once or twice a year or even at all. One approach was to take it out for inspection and cleaning or replacement at least once each year, so you could be pretty certain of its condition and, no doubt, to make sure replacement was always seen as a practicable (perhaps even desirable) option.

The other approach was to carry out a thorough inspection and condition appraisal and to use that as the basis of a judgement on which to base the decision of whether or not to remove the whole fill. Having read the paragraphs above, I invite you to read paragraph 138 of the Health and Safety Executive's guidance in L8 and reach your own judgement as to what the clarification of this question is likely to be when the HSE publishes its guidance supplement, drafted after external consultation.

Further information

Giles Green, Principal Scientific Advisor, Bureau Veritas, Tel: 020 8296 5700, Email: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it , www.bureauveritas.co.uk

 
< Prev   Next >
[ Back ]