It has been suggested that to obtain accurate data for trace metal analysis of drinking water, immediate acidification at the time of collection is necessary. However, because of problems encountered by EPA in field operations and epidemiology studies, further investigation into this requirement was pursued. Drinking waters containing known concentrations of lead were acidified at different time intervals after collection. The water samples were then stored at room temperature for varying time intervals before analysis for lead. For each time period there were seven samples with three aliquots from each taken for analysis in duplicate by flameless Atomic Absorption Spectrophotometry (AAS). All samples that were acidified gave a higher lead value than those samples containing lead but were not acidified. There were lead recovery variabilities among the time periods studies, however, it was evident that acidification of water samples after collection could be delayed up to 14 days without any adverse effect on lead concentration data.