Sampling Irrigation Water
A laboratory analysis is no better than the sample submitted for analysis. The sample should represent the conditions of use as much as possible.
Sample Bottles: Bottles should be clean. Plastic bottles should be used. At least 1 pint of sample is required.
Sampling Technique: Before filling, rinse the sample bottle out two or three times with the water being collected. Fill the bottles completely and cap tightly.
Lakes and Reservoirs: Choose location, depth, and frequency of sampling depending on local conditions and the purpose of the investigation. Avoid surface scum.
River or Stream: Sample from the middle at mid-depth.
Wells: Be sure the pump has been delivering water for at least 30 minutes. If the well is new, a sample taken after several hours’ delivery should be more representative than the samples taken earlier.
Distribution Systems: Flush lines sufficiently to ensure that the sample is representative of the supply.
Handling and Storage: Avoid sample agitation and prolonged exposure to air. Identify each bottle by attaching an appropriate label. Submit the samples for analysis as soon as possible. (Ideally the samples should be analyzed within 24 hours after sampling.) Keeping the samples cool (preferably refrigerated) and covered from light will reduce changes in sample composition between sampling time and analysis by the lab.
For a more in depth guide to collecting water samples, please visit this article.