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Preventing the Spread of Bacteria in Water Treatment Systems

For a number of years, the beginning and end of water treatment in HVAC systems has been to control the growth of legionella. This remains a prominent issue and new HSE guidelines have recently been issued to further advise organisations on how to control this, but further new legislation has also been published to highlight another danger lurking in closed water systems; pseudomonas.

The problem of bacteria growth

Many commercial and industrial properties have storage tanks, heat exchangers and miles and miles of piping, often many decades old, and these offer warm, humid conditions in which stagnant water provides a thriving breeding ground for a breakout of pseudomonas. These bacteria produce a biofilm, or slime, which left to grow in dead leg areas – lengths of pipework or storage areas where water can stagnate – can cause, at the very least, reductions in efficiency, but as a worst case scenario severe corrosion and blockages in pipework. This can become costly in terms of repairs and downtime.

There are many control systems available to monitor and restrict legionella growth, and these usually focus on the dosing of chemicals. Often, particularly if done in-house, this can lead to problems if the chemicals are over-dosed (ie. damage to pipework or other equipment can result) or they can be under-dosed if operators dilute them to prevent harm when handling them.

New legislation

Monitoring water treatment systems and controlling the potential spread of legionella and pseudomonas should be outsourced to qualified contractors, particularly now, with the HSE’s L8 Approved Code of Practice calling for facilities with complex water systems to create an asset register, a schematic diagram and to identify possible sources of contamination. Clearly, some expert knowledge is required here.

Furthermore, the rise in issues with pseudomonas has led many people in the industry to highlight the need to fight bacteria growth at the design and construction stage. If pseudomonas are left untreated they can be hard to remove once the bacteria has taken hold. So the latest BSRIA guidelines have called for ‘pre-commissioning cleaning’ as a standard requirement of all new closed water installations, in the knowledge that this is far easier and effective than cleaning an existing system, which will never provide an ‘as new’ status.

Pre-commissioning cleaning for the total approach

The guidelines now call for a ‘total approach’ which begins when a water system is constructed and continues during operation, and after this with ongoing monitoring and maintenance. There are several different types of pre-commissioning cleaning techniques, all of which will present a conditioned system free of bacteria build-up, and therefore allow an organisation to begin using a system in the knowledge that they can then control and restrict the growth of legionella and pseudomonas.

This ongoing monitoring and maintenance can be outsourced to industry experts such as Robinsons, who have years of experience in the design, installation, commissioning and maintenance of HVAC systems. We always adopt a ‘total approach’ and in designing your system can advise on the most appropriate pre-commissioning cleaning techniques to prevent bacterial growth, and can also take responsibility for the ongoing monitoring of your system.

Controlling legionella has historically been about remedial chemical treatment of a working system to create as near to a ‘clean’ system as is possible. But now, the emergence of pseudomonas has added more focus, and the best way to prevent their growth is to avoid dead legs in a system, where possible, to create a by-pass or flow around if it is not practical or cost-effective to remove dead legs, and to pre-clean a newly-commissioned system and employ contractors to maintain it. For all these solutions, Robinsons are perfectly placed to help you achieve this. Contact us today for more information.

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