Bleach Does It All on the Dairy or Does It?

"I just added some bleach to it."

This casual remark reflects a widely held belief throughout the dairy chain that bleach is a universal disinfectant suitable for a range of purposes, regardless of context. Bleach is inexpensive, readily available, and effective when used properly in appropriate situations. If bleach is a go-to in your dairy farm or processing facility, or if you are looking for cost-effective alternatives when margins are tight, there are some key points to keep in mind when using bleach.

All Bleach Is Not the Same

Per the Environmental Protection Agency (EPA) registration information, bleach is listed as a sanitizer for use on dairy equipment because it dissolves milk solids and other proteins. Chlorine products are also known for their ability to kill microorganisms, including pathogens and spoilage organisms. To ensure you use the right bleach for the task, read the labels when purchasing. Avoid purchasing scented, concentrated, or gel bleach for dairy food production, as the odor may be absorbed and adhere to the recommended concentrations. The liquid form of bleach is sodium hypochlorite. The powder or tablet form is calcium hypochlorite.

Best Practices for Use

Typical household bleach is a 5-9% sodium hypochlorite solution (CDC, 2024). The concentration of sodium hypochlorite and the intended use of the bleach are tied to the necessary contact time, or the amount of time the surface or contaminated object is exposed to the sanitizer. Additionally, the instructions require contact time (exposure time) of at least 2 minutes with a solution concentration of 200 ppm available chlorine as determined by test strips. This effectiveness also depends on a water temperature of 75°F. The EPA bulletin states that exposure time should be doubled for every 18°F drop in temperature. In other words, at 57°F, a contact time of at least 4 minutes is needed. This timeframe and temperature do not align with the contact time for teat dips in a proper milking routine, which is one reason to avoid adding bleach to teat dips. Also, keep these water temperature requirements in mind when using a bleach solution prepared and used throughout your milking routine.

The manufacturer's instructions reinforce that organic matter can tie up free chlorine, reducing the sanitizer's effectiveness, so cleaning surfaces and equipment first to remove soils is critical. Sanitizing is a separate step in the process. The manufacturer specifies use on metal, rubber, and other surfaces, and recommends a 200 ppm solution. Once surfaces and equipment are sanitized, they should be allowed to air dry and should not be rinsed again. The drying time contributes to the contact time with the sanitizing agent. Use of chlorine products on metals can cause corrosion due to oxidation, so monitoring the condition of surfaces and equipment is necessary.

While it is standard practice in the food industry to allow sanitizing solutions to dry on the surface, this practice has also prompted additional research. Questions have been raised in the European Union about the public health implications of chlorine residues, including their toxicity and resistance (Slattery and Garvey, 2025). Another study conducted in Ireland found that cleaning agents used in the bulk tank and on cleaning equipment had little impact on the microflora, whereas the season and farm location were more influential (Yap et al., 2021).

While not the focus of this article, it is worth noting other chlorine-derived compounds that are used in the dairy industry. These include chlorhexidine, used in teat dips; chlorine dioxide, used in teat dips and as a disinfectant for water and equipment; and hypochlorous acid for sanitizing surfaces. To avoid residues that could enter the food chain, the International Dairy Federation (IDF) (2025) recommends using chlorine products as directed on the manufacturer's label for the intended purpose and ensuring proper drainage of equipment. Additional best practices from the IDF include avoiding prolonged storage of sodium hypochlorite, rinsing when appropriate, and storing products in cool, dark environments.

Safety precautions should be taken when using bleach on the farm or processing facility. Airborne exposure can cause irritation of the eyes at 1 ppm with more severe health effects resulting at concentrations of 5 ppm or greater (USDA FSIS, 2020). Extreme caution should be used when mixing bleach. Bleach products should not be mixed with acidic products, with alcohol, or with other cleaners (Rovai and da Costa, n.d.). The manufacturer’s instructions are clear that bleach should not be mixed milk stone removers (US EPA, 2016). Wearing personal protective equipment (PPE) such as gloves, protective eyewear, protective clothing, and mixing solutions in a well-ventilated environment are necessary precautions. Wash your hands after handling bleach.  

Bleach remains a widely used and effective sanitizer throughout the dairy chain, but its benefits depend on selecting the correct product and applying it under the right conditions. Understanding differences in formulations, adhering to recommended concentrations, temperatures, and contact times, and recognizing the role of thorough cleaning before sanitizing are essential for achieving microbial control. At the same time, concerns about residues, equipment corrosion, and worker safety underscore the importance of following label directions and established best practices. When used thoughtfully and responsibly, bleach can be a valuable tool in dairy operations.

References

International Dairy Federation. 2025. Control of chlorine and hypochlorite residues in the dairy chain. Factsheet of the IDF N° 45/2025.

Rovai, M, and da Costa, LB. n.d. The use of bleach in dairy farms cleaning routine – basic information and precautions.

Slattery, M, and Garvey M. 2025. Chlorine disinfection byproducts: a public health concern associated with dairy food contamination. Dairy 6:18. DOI:10.3390/dairy6020018.

Yap, M, Gleeson, D, O’Toole, PW, O’Sullivan, O, and Cotter, PD. 2021. Seasonality and geography have a greater influence than the use of chlorine-based cleaning agents on the microbiota of bulk tank raw milk. Applied and Environmental Microbiology 87(22):e01081-21. DOI:10.1128/AEM.01081-21.

United States Department of Agriculture Food Safety Inspection Service (USDA FSIS). 2020. Chlorine health Hazard information sheet.

United States Environmental Protection Agency. 2016. EPA Reg. No. 5813-100 PUMA Service bulletins.