How To Achieve Adequate Trench Drainage
Updated: Jul 1
Food safety, hygiene, and cost control are all dependent on adequate drainage systems, and having floors pitched to drains is imperative to maintaining a sanitary food and beverage facility.
Oftentimes, poor drainage can lead to food contamination or the closure of a facility. At a minimum, inadequate drainage will lead to inefficiencies and a higher lifetime cost for facility maintenance.
Achieving Proper Drainage
First, an SQF specialist or resinous flooring expert should be contacted in order to figure out the floor drain layout, elevation calculations, and to handle related issues. The layout and type of drains will be dictated by the amount and properties of liquid runoff in your facility.
Standing water is an absolute breeding ground for pathogenic and non-pathogenic microorganisms. To prevent this, the floor needs to be adequately pitched at 1-2% grade towards drains.
If the floor is under pitched, you will end up with standing water. If the floor is overpitched, you will have solids run-off. An over-pitched floor will also increase the height of the floor around the perimeter of the room.
A proper pitch to achieve is estimated at ¼ inch height per linear foot, plus an additional 2.5 inches to the perimeter height of the room for every 10 feet from the drain.
Cleaning The Drains
According to data from the USDA, nearly 40% of pathogens, including Listeria, are found in floor drains inside food and beverage processing facilities. To prevent this, food processing drainage systems require thorough cleaning every day.
Proper cleaning methods include scrubbing the surface of the drain and implementing a pre-operational ATP or other swabbing program to ensure the drains are clean prior to start-up.
Choosing The Proper Drainage System
Choosing a drainage system that can minimize your cleaning and labor costs is one of the best ways to ensure your facility will be sanitary. In most cases, stainless steel trench drains are recommended, as they can handle extreme temperatures and resist bacteria.
You will also want to make sure the drains are labeled as food grade, have built-in slopes to prevent standing water, have smoothed edges and rounded corners, and have sealed connections or full welded joints to prevent the growth of Listeria in non-accessible areas of the drain.
Proper drainage is also necessary for passing strict FDA and USDA guidelines. Listed below are the FDA and USDA guidelines for drainage systems.
You should take steps to prevent the accumulation of standing water in or around drains, because standing water in your plant can be conducive to contamination with L. monocytogenes.
Examples of such steps include:
Designing and constructing the plant in a way that will make drains function adequately
Designing and constructing the plant in a way that will make drains adequately accessible for cleaning
Not installing trench drains in areas where RTE foods are processed or exposed and, where practical, replacing existing trench drains with enclosed plumbing to a floor drain
Designing and constructing drains so that the drains do not flow from areas where raw foods are processed or exposed to areas where RTE foods are processed or exposed
Designing and constructing drains so that restroom drains are not connected to drains serving areas where RTE foods are processed or exposed
Designing and constructing the slope of floors to drains so that floors drain freely and water does not accumulate
Not locating sewer lines above areas where RTE foods, FCSs, or food packaging materials are processed or exposed
6-202.19 Outdoor Walking and Driving Surfaces, Graded to Drain.
Exterior walking and driving surfaces shall be graded to drain
6-201.13 Floor and Wall Junctures, Covered, and Enclosed or Sealed.
In food establishments in which cleaning methods other than water flushing are used for cleaning floors, the floor and wall junctures shall be covered and closed to no larger than 1 mm.
The floors in food establishments in which water flush cleaning methods are used shall be provided with drains and be graded to drain, and the floor and wall junctures shall be covered and sealed.
4-204.120 Equipment Compartments, Drainage.
Equipment compartments that are subject to accumulation of moisture due to conditions such as condensation, food or beverage drip, or water from melting ice shall be sloped to an outlet that allows complete draining.
4-202.12 CIP (Clean-in Place) Equipment.
CIP equipment shall meet the characteristics specified under 4-202.11 and shall be designed and constructed so that:
Cleaning and sanitizing solutions circulate throughout a fixed system and contact all interior food-contact surfaces
The system is self-draining or capable of being completely drained of cleaning and sanitizing solutions
CIP equipment that is not designed to be disassembled for cleaning shall be designed with inspection access points to ensure that all interior food-contact surfaces throughout the fixed system are being effectively cleaned
4-202.16 Nonfood-Contact Surfaces.
Nonfood-contact surfaces shall be free of unnecessary ledges, projections, and crevices, and designed and constructed to allow easy cleaning and to facilitate maintenance.
Maintaining proper drainage adherent to USDA and FDA guidelines is essential to ensuring a hygienic facility and avoiding a plant shutdown.