Bacteria crisis warning ­ fight cancer-like attacks in pipework

Facilities

ISSN: 0263-2772

Article publication date: 1 September 1998

39

Keywords

Citation

(1998), "Bacteria crisis warning ­ fight cancer-like attacks in pipework", Facilities, Vol. 16 No. 9/10. https://doi.org/10.1108/f.1998.06916iab.005

Publisher

:

Emerald Group Publishing Limited

Copyright © 1998, MCB UP Limited


Bacteria crisis warning ­ fight cancer-like attacks in pipework

Bacteria crisis warning ­ fight cancer-like attacks in pipework

Keywords Bacteria, Water industry

Owners and tenants of many of Britain's most prestigious buildings could be facing a bacteriological attack on their services pipework and systems. Pseudomonas bacteria, once only 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 have the ability, through corrosion, to turn a chilled water system, or indeed any other open or closed system, into a sprinkler system.

Alan Fenn (Consulting Engineers' managing director), 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 nation-wide 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 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 tend to dismiss the problem, but it won't go away, so we are taking the lead," says Alan Fenn. "We are laying down guidelines relating to work to be carried out prior to the pressure testing until final dosing and operation is completed."

Elizabeth Day, water treatment specialist, 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 hosepipes, or little-used mains pipework. Such water may be seen as acceptable for the pressure testing exercise itself, but it is the residue that often remains inside the pipework that causes the problems. If pseudomonas and other harmful 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 ionisation. The slow corrosion process has therefore begun undetected.

Left unchecked, the film will increase and debris will accumulate, slowing down the waterflow 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 are not designed to remove micro-biological contaminants, they fail to make contact with the iron oxide on the pipework under the biofilm, and so the clean becomes ineffective.

Biocide, added at the end of the cleaning and flushing process, will remove some or all of the biofilm 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.

Elizabeth 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."

However, she points out that once the bacteria are present, their removal can be difficult; the more complex the system, the more difficult the access, and the higher the building occupancy levels the greater the problem of elimination.

FHP 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 per cent ­ and in many cases much more ­ of eradication costs if the bacteria go 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.

For further information please contact Alan Fenn, FHP Consulting Engineers, 178-202 Gt Portland Street, London W1N 6JD. Tel: 0171 631 0119; Fax: 0171 580 5840.

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