Water and Good Agricultural Practices
Water is one of the highest risks to food safety on a farm. We know that water is a vehicle that can contain chemical, physical, and biological contaminants. Water can carry and support many human and plant pathogens, weed seeds, viruses, parasites, and bacteria. Water also facilitates the transfer of bacteria, viruses, and parasites from one surface to another and therefore poses a potential risk for cross-contamination. Because water is used on the farm to perform multiple tasks involved in the growing and harvesting of fresh fruits and vegetables, risk assessment must be performed to prevent and reduce the risks that may be posed by water uses on the farm.
REMEMBER: Risk assessment is about risk reduction, not risk elimination. There can never be 100% risk elimination.
- Irrigation water that is applied overhead poses a higher risk than drip because the water is intended or likely to contact the edible portion of the produce.
- Drip irrigation under plastic poses the LEAST risk because water is not intended to, and is unlikely to contact edible portions is applied directly to soil and the plastic prevents splash-up.
- Flowers, stomata (pore openings in the leaves that allow air to penetrate into the tissues), and wounds are access points where water can enter into the plant, possibly carrying with it microbes. Once inside the tissues, further washing and sanitation is rendered ineffective and cleaning the plant.
2. Post-Harvest Rinsing/Cooling/Washing
- Water used in all post-harvest tasks should be DRINKING WATER QUALITY. Do not let efforts made to reduce contamination in the field go to waste by contaminating produce at the final stages of picking, packing, or rinsing.
- Keep excellent records related to water treatment in post-harvest activities.
3. Water Source
- Water for agricultural use is pulled from many sources. Municipal (city) water, well water, ponds, rivers, streams, and springs are all utilized for water on farms in Ohio. The source used can have a big impact on water quality. For example, a flowing open water source can have drastic changes in microbiology overnight while a closed and maintained well would see very little change, or contamination issues.
- Water should be of appropriate quality for its intended use. This means that all post-harvest water must be drinking quality, but irrigation water may not need to be as pure as wash water.
- Who decides what that appropriate quality is? At this point, water quality is largely dictated by GAP recommendations, some marketing agreements and local regulations, and customer demands.
- The most common quality standard for irrigation water used today is... water tested for generic e.coli should measure no higher than 126CFU/100ml.
4. Water Testing
Testing water at the point of application can help keep growers informed of the quality of water he/she is using, as well as to keep informed about events that may be impacting a water source.
*This is a list of laboratories, certified by the EPA, to test for microbes on drinking water. Not all labs may be equip to test surface water. Make sure to ask the lab about their capabilities and describe the water source you wish to be tested before commiting to a test.
Don't forget about the risk posed to the microbial safety of your produce from water that is out of your control, such as floods.