Bridging the GAPs: Approaches to Treating Water On Farms

Advantages and Disadvantages of Ozone

Ozone is highly effective at killing a broad spectrum of microorganisms, more so than chlorine or chlorine dioxide. Because it is generated onsite and immediately injected into water, it does not require transportation or storage of hazardous materials. Ozone offers an alternative to chemical treatment and does not produce harmful byproducts like trihalomethanes (THC) with the use of chlorine. In addition, it leaves no residue in the water. Along with its advantages, ozone does have several disadvantages. Ozone is highly toxic, and its use must be consistently monitored. Exposure to high concentrations of ozone can cause serious health effects. Proper ventilation is needed due to off-gassing during the ozonation process. The Federal Occupational Safety and Health Administration (OSHA) specifies an ozone limit of exposure at 0.1 ppm threshold continuous exposure during an Eight-hour period and 0.3 ppm for a 15-minute period. In addition to health concerns, its active life in water is approximately 20 minutes; therefore, it leaves no sanitizing residual for microbial reduction downstream of injection. In addition, there are capital investment costs for ozone equipment that may be cost-prohibitive. Growers should carefully size the equipment they need for their water flow and treatment, which will require professional installation. Ozonation equipment also requires a source of electricity at the treatment site, which may preclude its use in remote agricultural field locations.


Various approaches are available to treat irrigation water. Growers must weigh the benefits and costs of each approach and analyze which is best for their operation. An important aspect, regardless of treatment option, is understanding that EPA registered pesticide products must have a label that growers are required to follow for effectiveness and safe use. These instructions provide limits for use, i.e., whether it is approved for use in irrigation water, concentration, and contact time. The Produce Safety Alliance provides a searchable database of sanitizers approved for use on farms and packing houses. This database provides a direct link to EPA labels for further information on approved uses. Growers must keep in mind that any investment made should help achieve the ultimate goal of inactivating and reducing the risk of foodborne pathogens.


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