Bacteria Crisis warning to UK building owners
Owners and tenants of many of Britain's most prestigious buildings could be facing a bacteriological attack on their services pipework and systems which could have devastating results. Pseudomonas bacteria, commonly found in lakes and puddles, are now being detected in mains water, and although they pose no danger to public health, they can lead to damaging blockages and major corrosion of HVAC pipework.
The bacteria has the ability, through corrosion, to turn a chilled water system or any other open or closed system, into a sprinkler system. FHP ESS joined forces with other specialists to increase awareness of the problem and provide independent technical advice to clients.
Key personnel include the well known independent water treatment specialist, Elizabeth Day, and Alan Fenn of FHP ESS, who are working on 'the drafting of detailed requirements for new and refurbished buildings' which will, in effect be a new industry standard. They are also currently discussing the problem with BSRIA.
Alan Fenn says that as the problem is as much an engineering dilemma as it is a biological phenomenon, it is vital that procedures are instigated by qualified engineers working alongside experienced biologists that allow early identification of bacteria in the water system. "It is time this problem was brought into the public domain" he says. 'It could very well become a nationwide problem for the building industry, for although the bulk of the cases detected so far have been in London, particularly in the City, instances of the bacteria have been reported all over the country."
Pressure testing of closed systems (LTHW and chilled water) has been identified as one of the critical points when bacteria such as pseudomonas are often introduced into a system - a point far in advance of the arrival of the water treatment company to execute its routine procedures.
"People do tend to dismiss the problem, but it won't go away so we are taking the lead" says Alan, 'We are laying dawn guidelines relating to work to be carried out prior to the pressure testing until final dosing and operation is completed."
Elizabeth points out that water used in the filling and pressure testing procedure is often not the purest when it enters the system pipework. Even if it is taken directly from the mains supply, it may be via a stagnant storage container and- passed through unsterilised hose pipes, or little-used mains pipework.
Such water may be seen as acceptable for the pressure itself, but it is the micro-organisms that often remain and reproduce inside the pipework that cause the problem. If pseudomonas and other bio-film forming micro-organisms are contained in this residue they will multiply, forming a microscopic jelly-like film around the inside of the pipes. These anaerobic conditions protect the growth of Sulphate reducing bacteria between the film and the pipework, leading to microbial corrosion. The slow corrosion process has therefore begun undetected.
Left unchecked, the film will increase and debris will accumulate, slowing down the water flow through the system and creating clogging of small bore control valves and fittings. At the same time the corrosion will proceed until eventually leaks occur. As cleaning chemicals used by water treatment companies to remove iron oxide from pipework are not designed to remove micro-biological contaminants, they fail to make contact with the pre-commission debris in the pipework under the bio-film and so the clean becomes ineffective.
Biocide, added at the end of the cleaning and flushing process, will remove some or all of the bio-film and inhibitors dosed to the system to prevent long-term corrosion will then dislodge the exposed iron oxide remaining from installation stage. This will inevitably block strainers and the like. The system will appear dirty or aerated and commissioning will be either difficult or impossible. Liz Day says, "It is often difficult to regain micro-biological control - we are dealing with a living organism. When viewed in these circumstances it is like a cancer - if you don't get rid of it completely it will come back again."
And she adds, "Unfortunately, of those involved in the construction and running of buildings who are aware of pseudomonas and associated micro organisms, few are taking it seriously. Because it is harmless to public health, the water authorities are, understandably, not pursuing its elimination from the supplies; the bacteria cannot be seen, so contractors often turn a blind eye to it; and building operators will merely carry out declogging activity when small valves and low flow areas are affected."
"Closed systems need to be monitored and treated at both construction and maintenance stages to prevent and control problems of this nature. Whilst closed systems are the major concern at the construction stage, it is important to remember that bio-film formation on copper pipework (e.g. domestic water systems) can also lead to pitting and corrosion difficulties in the short and long term." However, she points out that once the bacteria is present, its removal can be difficult and the more complex the system, the more difficult the access, and the higher the building occupancy levels the greater the problem of elimination.
FHP ESS estimate that by demanding detailed testing and analysis, and incorporating safeguards into the prevention of pseudomonas entering a water system the building developer/user will be saving at least 50% - and in many cases much more - of eradication costs if the bacteria goes undetected at an early stage. Even though the existence of the pseudomonas bacteria and their potential danger to water systems has been more extensively known by some for a couple of years, there is generally no documentation on the matter - a situation that the team is now correcting.