Bookmark and Share

From: Food Quality & Safety magazine, June/July 2010

Drain Sanitation Delivers Peace of Mind

Using alternative cleaning methods can eliminate biofilms

by Adel Makdesi

When we think sanitation, we think cleanliness, and when we think cleanliness, we think about an effective food safety program and the peace of mind that results from it. That’s why food safety and cleanliness go hand in hand. A clean area means an area with clean surfaces, clean air, and clean surrounding environments. One of the definitions of “clean” is “free from dirt, filth, or impurities.” And to make clean is to remove dirt, filth, or unwanted substances.

In food plants, dirt, filth, and impurities refer to health-related extraneous materials that can be present in a food plant environment and on surfaces and that may contaminate food products and render those products unsafe for human consumption. These extraneous materials are classified under three different health hazard categories: physical, chemical, and biological contaminants. To prevent these extraneous materials from entering food products, the production team should first be provided with a clean and sanitary processing plant, a plant that contains the minimum amounts of extraneous materials and microbial contaminants. Also, some areas of the plant, such as the ready-to-eat (RTE) areas, should be free of particular microorganisms such as Listeria.

Providing the production team with a sanitary facility ensures peace of mind that the air, the walls, the floors, the drains, the belts, the coolers, the cooking kettles, and all other food contact and non-food contact surfaces, including the surrounding environment, will not contribute to food contamination. Their main efforts can then be focused on aspects of food safety related to preparing, cooking, packaging, storing, and shipping wholesome food products.

Have a Sanitary Facility

To provide a sanitary facility, plant management should adopt an effective sanitation program by working with the sanitation supplier to select the best cleaning/sanitizing chemicals, dispensing systems, and application procedures.

In a food processing plant, one of the main areas of concern is the floor drain system. Despite the continuous and increased efforts of many food processors to reduce the number of pathogenic microorganisms, particularly Listeria, in RTE-area drains, many drains have tested positive for these undesirable microorganisms. In fact, a 2004 audit of food processing facilities in a Midwestern state by the United States Department of Agriculture’s Food Safety and Inspection Service reported that 27.8% of floors and drains sampled tested positive for Listeria. This problem has left food processors puzzled and searching for an effective drain cleaning program.

Because most of the microorganisms, food residues, and other soils in food processing plants are funneled down into drains during the cleaning process, most microorganisms are found there, where optimal conditions for their growth and multiplication are readily available. And because the drain system (underground trunk lines) is difficult to access for an effective cleaning, food processors spend much money and labor trying to keep them sanitary, often with little success, especially when biofilm is present in the drains and at higher levels in the inaccessible underground part of the drain system.

Pathogenic and non-pathogenic microorganisms in drains typically take one of two forms. The first is free form. These are microbes that float in the drain water and are usually relatively easy to control and destroy with traditional sanitizers. In the second form, microorganisms are embedded in a biofilm.

The inside of a drainpipe before (A) and after (B) being cleaned with a foaming hydrogen peroxide/quat hybrid.
click for large version
The inside of a drainpipe before (A) and after (B) being cleaned with a foaming hydrogen peroxide/quat hybrid.

Biofilm Defined

Biofilm is a protective structure formed in drains by microorganisms when an adverse environmental condition strikes them. As microorganisms grow and multiply, they produce a chemical-resistant polysaccharide matrix, which they use to attach themselves to the drain system surfaces. Microorganisms in a biofilm exhibit high resistance to traditional sanitation chemicals.

In most cases, biofilms can be associated with a dark or light slime on the drain surfaces. The majority of the biofilm/slime is usually formed in underground drainpipes, where cleaners and sanitizers have very limited access, making it easier for pathogenic microorganisms to reside and multiply. This means that drains that are not cleaned and sanitized properly and regularly can become a major source of microbial contamination such as Listeria, Salmonella, and Escherichia coli.

Once in drains, microorganisms can be transferred to food processing and food service areas in various ways. For example, clogged drains can sometimes cause contaminated drain water to back up from the drains into the preparation area. Blocked drains can also create positive air pressure inside the drains, which will force the air to flow back from the drains into the preparation area, dispersing microorganisms through microbial aerosolization.

Another problem occurs when drains are cleaned with brushes using an up-and-down motion—instead of a circular and side-to-side motion—and rinsed with high-pressure water. This method causes all microorganisms in the drains to splash back from the drains onto the food prep equipment and food area floors.

Therefore, it is crucial, when cleaning drains, to use the right tools, chemicals, cleaning procedures, and frequency to eliminate any microbial problems in food processing and preparation areas. Without removing the biofilm matrix, it is impossible to kill the pathogens in drains.

If possible, floor drains in food processing and preparation areas should be cleaned and sanitized daily. If not, a thorough cleaning and sanitizing once or twice a week is recommended to reduce the number of pathogenic microorganisms in the drains. This can be achieved by either of two procedures:

  • cleaning drains using detergents, brushes, and sanitizers; and
  • cleaning drains using PerQuat technology (Zep Inc.), a foaming hybrid of hydrogen peroxide and a quaternary ammonium compound.
A foaming hydrogen peroxide/quat hybrid provides 360-degree coverage of pipes and can help attack biofilms.
click for large version
A foaming hydrogen peroxide/quat hybrid provides 360-degree coverage of pipes and can help attack biofilms.

Cleaning With Detergents, Brushes, and Sanitizers

This procedure, the most common one, starts with brushing the drains with a cleaning solution, rinsing them, and concluding with a flood sanitization using a traditional sanitizer. Although this procedure is effective, it can also be detrimental to the food safety program if sanitation workers are not properly trained. There are five critical elements to this procedure.

Brush size: The diameter of the drain brush should be at least 0.5 inch smaller than the diameter of the drain. Pulling a larger brush out of the drain will splash microbial cells back from the drains onto the food preparation surfaces.

Drain brush movements: As mentioned previously, brushing the drains with an up-and-down motion instead of circular or side-to-side motions will also cause microorganisms to splash from the drains onto food preparation surfaces, contaminating them with all sorts of microorganisms.

Rinse water pressure: Rinsing the drains with a large amount of water at low pressure is recommended to wash off all microbial contaminants and prevent them from splashing back onto the processing equipment and food contact surfaces.

Drain brush cleaning: Many workers place brushes on the floors when they are finished brushing the drains. This can contaminate the floors and surrounding area. After brushing the drains, workers should place brushes in buckets of a strong sanitizer solution and then clean and sanitize them in the cleaning area or janitorial sink. Drain brushes should be color-coded to separate them from the brushes that are used to clean food contact surfaces and equipment.

Underground drainpipes: This procedure is only effective in removing biofilm from the visible and accessible part of the drain. Unfortunately, the underground drainpipes that are not touched with brushes and sanitizers are covered with large amounts of biofilm and slime that can be transferred to the processing areas by different means.

PerQuat technology is based on a powerful chemistry between the negatively charged perhydroxide ion and the positively charged quaternary ammonium compound. Combined in one product, the two molecules form an intimate ion pair that results in a hydrogen peroxide and quat hybrid.

Another Cleaning Method

Use of a foaming hydrogen peroxide/quat hybrid is considered by many to be the most effective program for removing biofilms from drains. This method, known commercially as PerQuat technology, uses powerful chemicals to clean and sanitize the drains and their underground pipe-lines in one simple step.

PerQuat technology is based on a powerful chemistry between the negatively charged perhydroxide ion and the positively charged quaternary ammonium compound. Combined in one product, the two molecules form an intimate ion pair that results in a hydrogen peroxide and quat hybrid. This chemistry has a unique cleaning ability and antimicrobial efficacy against a wide range of microorganisms, allowing it to be used in a variety of industrial and public health environments. In fact, the chemistry is registered with the Environmental Protection Agency for the removal of biofilm from drain systems, whereas typical drain cleaners and sanitizers, including enzymatic cleaners, drain openers, or quat-based sanitizers, are not. In addition, these other products are ineffective against the pathogens found in biofilms.

PerQuat technology, represented by the BDQ bubbles, works to attack microorganisms embedded in biofilms.
click for large version
PerQuat technology, represented by the BDQ bubbles, works to attack microorganisms embedded in biofilms.

In tests conducted by the National Food Processors Association, bacteria on stainless steel chips survived after the chips were immersed in a variety of sanitizers for five minutes: hot water at 180°F; chlorine at 20, 50, and 200 parts per million (ppm); and iodine at 25 ppm. The only true germicide tested was a hydrogen peroxide/quat-based chemistry, which was found to be effective against biofilms at three percent and six percent solutions.1

Drain cleaning products based on this chemistry are easy to use and can be poured or preferably foamed into the drains using a simple foaming unit that forces the product into the underground drain pipeline via a foaming attachment or assembly that can be attached to the foaming unit with a quick connection. The foam travels as far as desired in the drainpipes, depending on drain system conditions.

As it travels, the foam covers all drain system surfaces, offering full 360-degree coverage. It penetrates and breaks down the biofilms from the surfaces of the drain, including the ceiling of the underground drainpipes. While breaking down the biofilm, it destroys microbial cells embedded in the biofilm. Because no scrubbing is required in the use of this technology, problems associated with the previously discussed method are avoided.

The hydrogen peroxide/quat hybrid chemistry is free of phosphates, acids, and chlorine and helps to control and eliminate fruit flies from the drains. Products that utilize this technology are also economical and efficient. It takes only 20 to 30 seconds to foam each drain, thus reducing the amount of time and labor required to execute a complete and effective drain care program. ■

Makdesi is corporate senior microbiologist at Zep Inc.; reach him at (404) 352-1680. For more information on eliminating pathogenic microorganisms and biofilms in food preparation areas, visit


  1. Felix CW. Sanitizers fail to kill bacteria in biofilms. Food Prot Rep. 1991;7(5):6.



Current Issue

Current Issue

February/March 2015

Site Search

Site Navigation