Lead poisoning is a major environmental health problem for children in the United States (1,2): during 1988-1991, approximately 1.7 million U.S. children aged 1-5 years had elevated blood lead levels (BLLs) (> or = 10 micrograms/dL) (3). To determine the source of lead exposure for children with BLLs > or = 20 micrograms/dL, the Arizona Department of Health Services (ADHS) conducts environmental investigations. In 1993, as a result of investigations of increased BLLs in two children in southwestern Arizona, ADHS detected lead levels approximately 30 times the Environmental Protection Agency (EPA) action level of 15 parts per billion (ppb) in bulk-delivered drinking water in the homes of these children. Because two of the three companies that supplied bulk water to southwestern Arizona were based in California, ADHS notified the California State Department of Health Services (CSDHS) about the problem. As a result, CSDHS conducted a separate investigation and identified one child with an elevated BLL whose drinking water sources included bulk-delivered water with lead levels exceeding EPA standards. This report summarizes the investigations of elevated BLLs in these three children and high lead levels in bulk-delivered drinking water in Arizona and California.