The public notification requirements of violations of maximum contaminant levels (MCLs) in drinking water were evaluated through a scientific sampling of residents of fifteen California communities. Each community had recently notified consumers of an MCL violation. The sampling assessed public awareness of the notification, the effects the media used had on awareness and knowledge of the problem and its solution, and the attitude of the respondents regarding the notification requirement and its effectiveness. Sixty-eight percent of the respondents were aware of the notification, thirty-nine percent knew something of the contaminant of concern, and twenty-nine percent understood something of the long-term solution necessary. Statistical analyses showed that awareness of the problem was influenced by whether the respondents paid water bills, not by the use of the electronic media. Statistical analyses also showed that knowledge of the contaminants of concern was influenced by awareness of the problem and the quality of the message, as was understanding of long-term solutions. Overall, ninety-four percent of the respondents recommended continuation of the program. Includes 6 references, tables.