Water Quality in Fruit and Vegetable Production
By Mark Zotti, Marketing and Inspection Representative
Like the human body, fruits and vegetables are composed mostly of water. Throughout the growing process, agricultural producers rely upon water for irrigating, fertigating (fertilizing using irrigation), drinking, washing, and cleaning. The quality of that water affects the overall quality of the consumed product. Proper testing and management is required to maintain this important tool and reduce the risk for microbial contamination.
It would be ideal if all water met drinking water standards, but that is unrealistic for most untreated surface water. Testing is the only way to know for sure if water is appropriate for its intended uses. This sounds simple enough, but when dealing with water in an agricultural operation, different uses may allow for different water quality standards. The first step in assessing on-farm water is to identify its use. This will help determine what the test results need to show.
Producers take great care when harvesting product and preparing it for sale. No one would knowingly apply contaminated water to a product. Water used just prior to harvest and through post-harvest activities should be tested to verify that it meets the State of Connecticut Drinking Water Standards.
The quality of the water used during post-harvest activities should be closely monitored. This includes water used in dump tanks, water baths, or final rinses. Foodborne illnesses have been linked to poor-quality water used in post-harvest practices. A variation between the temperature of the water and the fruit/vegetable coming in contact with that water can cause the product to absorb the water.
If there are any bacteria in that water, they, too, will be absorbed, leading to a potential foodborne illness. Many farm operations have temperature monitoring systems and/or water treatment systems that maintain water quality.
Any water used for drinking and hand-washing should also meet drinking water standards. For more information about drinking water standards and for a list of water-testing laboratories, see the drinking water section of the Connecticut Department of Public Health’s website at http://www.ct.gov/dph/cwp/view.asp?a=3139&q=387304&dphNav=|&dphNav_GID=1824.
Water used during other parts of an agricultural production process also needs to be evaluated. The quality of the water used in irrigation, fertigation, and spray applications will be determined by the crop, the type of application method, the amount of time between application and harvest, and post-harvest handling practices. It is important that growers take these items into consideration when assessing their water, its uses, and the quality of the water needed.
It is also important to note that certain agricultural products have a higher risk of contamination. Producers should take greater care when assessing water and growing practices on such items.
Fortunately water in Connecticut is fairly accessible. Understanding water sources, quality, and uses can help develop an on-farm strategy to maximize production along with the safest growing techniques. This will start with the water source.
Water sources fall into one of three categories: surface water, ground water, and municipal water.
Surface water used in farming operations generally comes from a stream, river, lake, or farm pond. The quality of this water often varies and may be subject to temporary contamination from a variety of factors. Potential contaminants can vary from previous land use, wastewater discharge, or upstream runoff.
These sources can be difficult to protect from outside contaminants and should be tested frequently before and throughout peak usage. In Connecticut, it is recommended that all surface water be tested at least three times:
1. prior to usage;
2. during peak usage;
3. prior to the end of usage.
Having surface water available can be an asset to farming operations but it is important to monitor its quality and properly use this resource.
Ground water is water that collects below the earth’s surface and is retrieved from a well. This type of water can be affected by surface water, so monitoring is important. These water tests should be performed twice a year:
1. before use;
2. during peak usage.
In addition to testing the well water, the well should be properly constructed and frequently inspected to maintain water quality and prevent outside contamination.
Municipal water is water supplied from a controlled water source and is closely monitored to verify it meets the State of Connecticut Drinking Water Standards. This option is often the most expensive but the quality will not impose usage restrictions.
When getting water tested, specify what the testing laboratory is testing for. Many labs provide testing for testing drinking water standards but infrequently test for other water quality standards.
Be specific when requesting what the test results should show. Request a test that identifies the presence of indicator bacteria. These indicator bacteria signify whether there is a presence of potential contamination. Request that test results show two measurements of the indicator bacteria:
1. geometric mean per 100 milliliters (XXX/100ml);
2. single-sample maximum per 100 milliliters (XXX/100ml).
If elevated levels are present, further testing is recommended to determine what specifically the problem may be.
The Connecticut Department of Energy and Environmental Protection Bureau of Water Protection and Land Reuse Planning and Standards Division provides Connecticut Water Quality Standards (WQS) that establish designated uses for surface and ground waters.
The WQS lists surface water classes AA, A, B as approved water supply for agriculture uses. WQS lists different water classes and the criteria (geometric mean/100ml and single-sample maximum/100ml) for each of these classes.
See http://ct.gov/dep/lib/dep/water/water_quality_standards/wqs_final_adopted_2_25_11.pdf for more information about water classes and indicator bacteria levels.
Remember, having a well-protected, good-quality water source is an asset to any agricultural operation. Even with such a resource, proper management tools are needed to maintain the integrity of that source.
Identify the intended uses of that water and get it tested. Poor water quality can be corrected. All producers should look at the products grown and assess their potential for microbial contamination based on production methods.
Unfortunately, there is no way to totally exclude a risk of microbial contamination, but by addressing the water sources and incorporating good agricultural practices, all growers can reduce their risk of microbial contamination.
Water may be a source that can lead to contamination, but it is also a tool that, when properly managed, can be an asset in producing the safest possible fruits and vegetables.