Fighting the water bug

The health service is not unique in combating legionella bacteria – the private sector also has to achieve the same goals. But there is no getting away from the fact that in the health service, patients are at greater risk as they fall within the most susceptible categories. These include those over the age of 45, immunosuppressed patients, smokers, diabetics, alcoholics and those with cancer or chronic respiratory or kidney disease.
    
Combating legionella is serious business; failing to monitor and prevent it could end up with imprisonment and considerable fines.

Arm yourself with guidance
To help you comply with guidelines, the first recommendation is to get yourself a copy of the relevant Hospital Technical Memorandum (HTM 2027 and NHS Estates 1998 ISBN 0 1132 2158 4) and also a copy of L8 Legionnaires’ disease - The control of legionella bacteria in water systems’ Approved Code of Practice & Guidance (ACoP).
    
Once armed with these documents, you are in a position to take the first steps. The fundamental rule with Legionnaires’ disease is that you have to remember that it is preventable. Unfortunately, this requires resources and the health service is already stretched in this area. Some of the biggest hurdles that the health service has to deal with in its fight against legionella are budget constraints, system design, health and safety procedures, experience, training and knowledge.

Health & safety procedures
It seems strange to say that improved health and safety procedures have had a detrimental effect on controlling legionella bacteria. But the introduction of the antibacterial gel hand washes that are found throughout the health service (used to prevent the spread of MRSA) has actually had a major effect.
    
It has been observed that sinks and outlets are now used considerably less as doctors and health carers use the antibacterial gels between treating or examining different patients rather than sinks. This means that the water in the supply system may not be flushed through as regularly as originally designed. The chance of water stagnation has increased as a result. And this is one of the major contributing factors to the proliferation of legionella bacteria; the risk of contamination as a result of stagnant water is now greater than before these procedures were implemented.
    
Some hospitals have identified this risk and have had to employ personnel to flush the outlets daily to prevent water stagnation. As you can imagine, this is a costly exercise. With the continued development of building management systems, there are solutions in the market that will use the latest technology to allow you to flush your systems automatically. These are not cheap and you have to consider the initial costs together with your annual labour cost. In some instances, however, it can be a cost effective solution.

Training
Training is another major issue. Partial knowledge can be as dangerous as no knowledge when dealing with legionella. I was recently discussing legionella control with a hospital engineer and he stated that as he has Thermostatic Mixing Valves (TMV) on his system, it was free from risk and he therefore has no need to carry out regular monitoring of the system. Although a TMV, because of its design, can appear to aid your legionella control, you have to remember this is not what they are designed for. They were originally designed to prevent scalding at the outlet when hot water systems distribute water at very high temperatures.
    
Distributing the hot water at high temperatures (in excess of 60˚C) will eliminate legionella, but once this water has passed through a TMV it is greatly reduced by mixing with the cold supply. Should the cold water supply be the source of contamination, you have a potential risk. Also, if there is a fault in the hot water supply, you could potentially increase the risk of contamination should the water be distributed at lower temperatures.
    
Even with TMVs in place, you should still monitor the temperature of your water system. The approved code of practice states that regular monitoring of the temperature should be carried out on the input to TMVs on a sentinel basis.
    
This confirms once again that the first step is to get your hands on the relevant guidance documents. There are also training courses available, which you should seriously consider. There is nothing wrong in admitting you don’t have all the answers and there may be improvements in legionella diagnosis, control and understanding since you last had training. If you are the person responsible for legionella control and you have not had previous training in this area then insist on it, it could save someone’s life.

System design
System design can also be a contributing factor. As most of the buildings in the health service have been around for quite a while now, the systems can be old and dated. They have certainly not been designed to take into account the new health and safety procedures associated with MRSA and the effects this has on system usage.
    
You can retrofit systems to flush and circulate your water but this can cause major disruption to the hospital, cost a considerable amount of money and reduce performance targets. You can also reduce the amount of stored water, but disruption and costs can be a concern. However, should the second stage (carrying out a Legionella Risk Assessment) identify any of these as remedial action, you must have the work carried out.
    
You must be in a position to carry out the appropriate measures and controls to ensure you have prevented the spread of the legionella bacteria by monitoring your system and the prevention measures you have identified in your risk assessment. This means having an adequate budget.

The first steps

• Identify and assess the risk
• Identify management responsibilities, training and competence
• Prevent or control the risk from exposure to legionella bacteria
• Monitor your water system and control measures
• Record keeping   

Treatment and control programmes available for distribution systems are:
    
Biocide Treatments (Not Permitted in NHS premises HTM 2027).

Chlorine Dioxide: You will need to confirm installation complies with Local Water Regulation. The monitoring required is regular (monthly) temperature monitoring of system (including sentinel outlets) and annual inspection.

Temperature Monitoring Regime: Regular (monthly) temperature tests at calorifiers and sentinel outlets, six-month temperature check of CWS and annual inspection.

Ionisation: A local water company may need to be consulted. For both hard and soft water the ionisation is pH sensitive. Scale and dissolved solids need to be carefully controlled. Additional water treatments may be required. Monitoring required is regular (monthly) temperature monitoring of system (including sentinel outlets) and annual inspection.

Microbiological monitoring:

• Cold water systems – Regular sampling from CWS tank, furthest outlet and areas of particular risk e.g. in hospital wards with ‘at risk’ patients.
• Hot water systems – Regular sampling from calorifier outlet and return supply, drain valves if fitted, the furthest outlet from calorifier and areas of particular risk, e.g. in hospital wards with ‘at risk’ patients.   

Cooling towers and evaporative condensers are of particular concern and as a whole need to be monitored monthly for water quality, water use, biocide/chemical use and condition monitoring of pond, pack and water. According to risk either monthly or three monthly check of the central control function, conductivity sensor calibration, blowdown function, uniformity of water distribution, eliminators, sprays/troughs, pack, pond, immersion heater, fans and sound attenuators. Six monthly clean and disinfection of system including all wetted surfaces must be undertaken. Descale as necessary.
    
If you are unsure of any of your responsibilities, there is advice available. The Legionella Control Association (previously Code of Conduct) has a large number of members that specialise in legionella. You also have to remember that under ACoP, you need to investigate the competence of anyone you may employ.