The Food Safety Modernization Act (FSMA) regulates irrigation water testing and what water needs to be tested. This article outlines a fine point that can make a big difference in the amount of testing required of growers.
As many growers are aware, the Food Safety Modernization Act (FSMA) is the most sweeping legislation in 70 years regarding raw agricultural products. FSMA spans over 500 pages and is extremely complex. One area of particular complexity is the issue of irrigation water testing and what water needs to be tested.
The act classifies two types of water used in the field: agricultural water and indirect water. If water comes into direct contact with the edible portion of a plant, it is considered agricultural water. If a grower uses overhead sprinklers to irrigate a lettuce field, it would be considered agricultural water. The second type of water is called indirect water. In this case, the water would not come into direct contact with the edible portion of the plant. If drip tape under plastic is used to maintain tomato plants, this would be considered indirect water.
Sometimes the plant stage dictates whether a particular type of water is either agricultural or indirect. Sprinkler irrigation of blueberries from bloom through harvest would be considered agricultural water. The same source of water delivered in the same way would be indirect water when used after completion of harvest.
These differences seem like small points, but they can have a big impact in the cost of sampling under FSMA. FSMA requires that surface water used for agricultural water be tested weekly for generic E. coli. There is no testing frequency proposed for indirect water.
(from Michigan State University)