Groundwater Sampling and Monitoring

Abstract

Water quality data are only as good as the water samples from which the measure-ments are made. Even the most precise laboratory analysis of a water sample cannot compensate for improper or poorly executed sampling procedures or for physical and chemical alteration of a sample due to inappropriate sample collection, transport, or storage. This publication summarizes a number of considerations that you should keep in mind when sampling ground water. The publication is specifically intended for use by farmers and private well owners who are interested in obtaining a proper water sample for screening purposes (bacterial concentration, nitrate, iron, pH, min-eral composition, salinity). Public water supply systems are subject to regulation by the California Department of Health Services, which specifies minimum guidelines for sampling frequency and sampling procedures that must be followed by any water sys-tem operator. Many analytical laboratories will provide services to help you sample well water properly and provide you with proper sampling containers. For an accurate determi-nation of the concentration of many pollutants that are regulated at low concentra-tions under drinking water standards, laboratories use relatively sophisticated sam-pling methods, so well or water system operators should seek the help and advice of a professional laboratory or consultant.