Lurking legionella

Contrary to urban myth, mains water supplied in Britain is of very high quality and reliably so; a cursory inspection of the statistics shows the percentage of failures to meet the standards required by the regulations is tiny and a little research will show that those standards are very high indeed. It is also available in seemingly inexhaustible quantities, just by opening a tap and at an astonishingly low price; compare it to bottled water which has to be carried home and may cost as much per litre as mains water costs per cubic metre, which is a thousand litres.    
   
Yet, as this is the real world, there can be no joy without alloy and this idyllic state of affairs is not the whole story by far. Common sense would suggest that the amount of water available is limited and, for those with none, the message comes across loud and clear in the press and on television. In fact, the water taken for the mains supply is a substantial proportion of all that is available, even here in rainy Britain.
   
Not only that, but the wholesome water from the mains is not sterile (it does not need to be either for health reasons or to comply with the regulations) and the few microbes which are present have the potential, if conditions are favourable, to multiply to levels which can be harmful. Probably the most dangerous of these is Legionella, the bacteria which cause Legionnaires’ disease.

LEGIONELLA BACTERIA
Legionnaires’ disease is frequently fatal and even when it is not, it is a very severe illness which can lead to long term debilitation. It is also completely preventable by simple and fairly inexpensive means and for that reason, it falls within the scope of what is considered under the Health and Safety at Work Act as “reasonably practicable”. This means that several other sets of regulations are applicable, not least the Control of Substances Hazardous to Health (COSHH) and Management of Health and Safety at Work (Management) regulations, which place requirements on anyone in control of a premises used in any enterprise to establish the degree of risk of Legionnaires’ disease at those premises and, if it is significant, to prevent or control it.
   
What usually follows a Legionnaires’ disease risk assessment is a report making recommendations to carry out minor repairs or modifications to the water systems and to operate a regime sometimes known as the Kingston Controls, which involves using only suitable materials which do not yield nutrients (which is required by law anyway); maintaining at least moderate cleanliness of the water systems (which seems far more reasonable than not doing so); maintaining control over the temperature of both cold and hot water (the cold arrives cold enough most of the time, and heaters and thermostats keep the hot water hot) and; not allowing water to stagnate (when the occasional Legionella bacterium which may be present in the mains water or from trace contamination within the system can multiply to dangerous levels). This regime is effective and sounds quite simple, but there are, in the real world, complications.

A WASTE OF WATER?
To keep cold water cold in warm boilerhouses, plantrooms, service voids and occupied space requires not only good insulation (which only slows and does not prevent heat gain), but also displacement to remove any water which has warmed and replace it with fresh. This is not a problem where systems are well used, but if there are areas which are underoccupied and times between terms when there is little or no demand for water, the classic Kingston solution is to flush water to drain weekly to compensate.  Is this wasting water, contrary to the Water Supply (Water Fittings) Regulations which replaced the Water Supply Byelaws in 1999?
   
Keeping hot water hot requires even more insulation than keeping cold water cold and the heat losses help create the warm spaces which heat the cold water. The same issues of underuse arise and the solution of flushing seems to waste energy as well as water. And if that is not enough to undermine faith in the regime, the temperatures required to control Legionella have the potential to scald.
   
So this leaves the person in charge with a set of regulation-backed conflicting requirements with environmental considerations for good measure, all in the context of preventing an especially nasty disease: the resolution is as simple as it is difficult, just as might be expected in the real world.
  
The person in charge is considered to be responsible, so he or she is expected to be able to make and implement decisions. In fact, this person should be senior enough to hold a budget, to place contracts or make appointments and to ensure any contractors or appointees carry out their duties fully and correctly. Such a person would also be expected to be capable of considering risks in the context of other risks or environmental issues and to strike a suitable balance. Let that person consider the conflicts in turn.

FLUSHING WATER TO DRAIN
The regulations make wasting water an offence, but they do not prevent usage and they are not prescriptive about what constitutes usage. Flushing water to drain to preserve its quality could quite reasonably be considered usage, as the water was being used to preserve the quality of the water being consumed by users. If there are no users, for example when an area is mothballed, repeated flushing over a prolonged period (for example more than 60 days) would probably be considered wasteful. So the person in charge has to decide whether to decommission the system or mothball it, secured against unauthorised use and reinstate it when it is needed.
   
If flushing moderate amounts of water to drain is using, not wasting, the water, reason demands that it is using, not wasting, energy. In fact, flushing with hot water can have a disinfecting effect. The issue of heat loss from hot pipes and raising the temperature of service spaces is easily moderated with more insulation and adequate ventilation, options which are more often not taken either because installation works are not adequately specified and supervised or on cost grounds than for any good reason.

SCALDING
The hands of a normally fit and healthy person are not very susceptible to scalding in water up to 60°C because the time required to sustain a clinical injury is several seconds and the pain for the first few of those seconds is difficult to bear. Small children, the elderly and infirm may be at considerably greater risk and dedicated mixing devices should be used at washbasins, baths, showers and bidets to protect them. Other parts of the body are also more susceptible to scalding and showers usually have some temperature limiting device. But even when these were less common, real injuries were very rare among the normally fit and healthy.

In conclusion, water management is serious, requiring specialist assessment and a measured regime of controls to strike the right balance between risks and other issues; otherwise this superbly crafted and precious essential of all life will show just a little too much of its real world potential.