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Controlling contamination - Drainage is a potential breeding ground for micro-organisms but intelligent design, specification and installation can minimise the risk of contamination

In every food or beverage processing facility the weak spot in effective hygiene control lies buried underfoot: the drainage system.

Drains provide an ideal breeding ground for pathogenic and non-pathogenic micro-organisms. These typically occur either as free form, where microbes float in the drain water, or embedded as biofilm. In each case they create the potential for transferring pathogens, including Listeria, monocytogenes from the drain to food products.

Controlling these micro-organisms depends on a number of factors: careful design of the drainage system, correct choice of materials and installation techniques, efficient maintenance and an effective sanitisation regime. The right considerations made in these areas will allow plant and maintenance engineers to minimise and control the risk of contamination.

From the outset, drainage must be specified in line with sanitary design principles. Health risks can be minimised by providing appropriately located floor drains of adequate number and capacity. Cleaning and maintenance should be considered early on to allow hose stations to be provided in appropriate locations.

It is also advisable to use drainage products that are easily cleanable. The ACO Gully range, for example, is constructed from highly corrosion-resistant austenitic stainless steel, ideal for hygiene-critical applications such as food manufacture as its non-porous state enables easy cleaning and disinfecting.

The new range of ACO Gullies have been specifically designed to accommodate Regulation (EC) 852/2004 Hygiene for Food stuffs where the range and products have been designed in accordance with British and European standards for hygienic design and food processing equipment to provide the end - user with optimum hygiene performance.

Point gullies with catch baskets to collect debris are generally the most appropriate, provided they are well specified and fitted. Linear drainage systems are a common alternative but these must be carefully constructed and installed as an inadequate fall to outlet may present the health hazard of standing water.

Having installed a robust, cleanable, efficient series of drainage products, the next consideration is maintenance. Drains offer the optimal conditions for the growth and multiplication of micro-organisms and, because the drain system can be difficult to access, effective cleaning is a major challenge.

There are two types of pathogenic and non-pathogenic micro-organism: those that are ‘free form’ and those that are embedded in a bio film. The former can be destroyed with traditional cleaning products, while the latter are far harder to kill. These embedded micro-organisms have developed a polysaccharide matrix or bio film to defend themselves from chemicals and they use this protective film to attach themselves to the drain system surfaces. These bio films are sometimes visible as a dark or light slime on the drain surfaces. They can become a major source of microbial contamination such as Listeria, Salmonella, and Escherichia coli.
There are several ways to prevent these micro-organisms from entering hygiene-critical areas. Clogged drains can cause contaminated waste water to back up into the preparation area, or force the air from the drains to flow into it. It is vitally important, therefore, especially in food preparation applications, that any developing blockage is addressed immediately.
Another way of minimising hygiene risk is to regularly clean accessible areas of the drain with a circular and side-to-side motion rather than an up-and-down motion, a simple precaution that prevents splashback of contaminated water onto the floors of food preparation areas. Rinsing with high-pressure water presents the same danger of splashback so keep the pressure low. Having cleaned the drain, clean the brushes with a strong sanitizer and keep them well away from food contact surfaces and equipment. Better still, colour-code them to reduce the danger of brushes being used inappropriately or stored in close proximity to food. These relatively small measures will significantly reduce risks to health and safety.

Underground drainpipes cannot be reached with brushes and, naturally, these are often coated in bio film. These can only be tackled with strong chemical products that penetrate and break down the bio films.
Access can be difficult and both free form and bio film micro-organisms hard to destroy and so a daily clean is the best way to prevent a build-up that will become increasingly harder to control and, with careful, regular cleaning, it is then possible to eliminate most microorganisms from food or beverage processing facilities.