Testing irrigation water for generic E. coli is something that every farm should do. Timing and frequency of this testing varies depending on your water source. Here is a cheat sheet:
| Frequency | Timing | Corrective Actions | |
| Municipal Water Source | Once per year | Obtain municipal water reports and keep on file (often available online) | N/A |
| Well Water Source | Once per year | Sample for generic E. coli, ideally at the beginning of the season | Water test reports indicating well contamination will need to be treated before utilizing the well as a water source. |
| Surface Water Source | Three times per year | Sample for generic E. coli at planting, at peak use and at or near the first harvest. | Surface water should not come in contact with harvestable product. In-line treatment systems can be used to reduce generic E. coli loads in the water. |
The current guidelines for irrigation water are 235 CFU or MPN generic E. coli per 100 ml water for one sample and 126 CFU or MPN generic E. coli per 100 ml water for a five sample average. Consider treating the irrigation water if the results are above the guidelines.
The Food Safety Modertization Act will most likely require greater frequency in sampling of well water and surface water sources. We will keep you updated as we learn more about the rule.
For more information on irrigation water testing visit the Cornell Good Agricultural Practices Agricultural Water page.
