The major source of error when obtaining water quality information is improper?

Improper sampling is indeed a major source of error when obtaining water quality information. Sampling refers to the process of collecting a portion of water for analysis to represent the overall water quality of a larger body of water. If sampling is not conducted correctly, the sample may not accurately reflect the characteristics of the whole, leading to misleading results.

For example, if a sample is taken from a location that is not representative of the overall water source, or if the timing of the sampling does not account for variations in water quality (such as peak flows after rainstorms or during certain times of the day when pollutants may be higher or lower), the data gathered could be significantly skewed. Proper sampling techniques, including determining the right location, time, and method for collection, are vital in ensuring that the data obtained for water quality assessment is reliable and valid.

Issues such as improper testing methods, contamination of samples, or inadequate calibration of equipment can certainly affect results; however, if the sample collected is not appropriate to start with, any subsequent measurement or analysis will not yield accurate information about the water quality being evaluated.