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City of Pleasanton Water Quality Division's Report on Water Quality Relative to Public Health Goals 2022 June 2022 -Page 3 of 8 INTRODUCTION The City of Pleasanton's Drinking Water Public Health Goals Report 2022 is required of larger public water suppliers by the California Division of Drinking Water(DDW) California Health and Safety Code, Section 116470(b). The report is intended to provide the public and decision makers with specific information regarding drinking water safety so they can consider further purification of water to move its quality closer to health goals. The City's Annual Water Quality Report, issued each year by the City and available to all residents and businesses receiving water from the City,reflects the responsibility to which we provide this critical resource to the City's 79,871 residents. As these annual reports show,the water that the City of Pleasanton provides consistently meets, or is superior to, enforceable federal and state water quality standards. This report documents the drinking water constituents in our water supply found to be above their respective state Public Health Goal(PHG)or federal Maximum Contaminant Level Goal (MCLG) based on the analytical data from samples collected in 2019, 2020, and 2021. Both the PHGs and MCLGs represent non-enforceable goals for the level of constituents, which may be present in a water supply, at which a minimal risk to public health is expected. These goals are developed based upon the health effects data available in current scientific literature. The process of establishing water quality standards begins by calculating a theoretical level at which a contaminant may be present in drinking water without causing adverse health effects. This level, which assumes minimal to zero risk, is called a"goal" and often is not practically achievable because the technology to remove a contaminant to that level may not exist, or the cost to do so may be prohibitive. Nevertheless, the goals are useful tools for regulators when determining standards, or MCLs, that water suppliers are obliged to meet. It is important to maintain perspective about the theoretical nature of the numerical risk presented in this report. The state agency that develops the PHGs understandably does so in a very conservative manner and often must do it with limited scientific data. There is often a need for additional scientific research to substantiate the established goals. Hence, there is a need to balance the risk associated from exposure through drinking water with that of other environmental factors and human behavior. The report elaborates on three important aspects of drinking water safety: The first, is that drinking water, even if it is in full compliance with existing water quality standards, may expose customers to a level of risk, although very low in comparison with other sources of health risk. The second,. is that there can be significant costs and technology limitation associated with water treatment to reduce such low risks. Third, no public water supply can meet all PHGs and MCLGs. 3