A number of organizations engaged in tanker trucks to deliver water to populations affected by the 2005 tsunami in Indonesia. Many relief organizations assumed that the trucks provided safe water, even promoting tanker truck water as safe water; however, no surveillance systems were in place to monitor tank truck water quality. We surveyed 40 tanker trucks operated by 12 organizations. A total of 75 water samples were tested for residual free chlorine, and of these, 54 were also tested for E.coli. Of the 75 trucks tested for free chlorine, 42 (56%) had adequate chlorine residuals (greater or equal to 0.1 mg/L). Of the 33 samples with inadequate chlorine residuals, 27 (81.8%) reported having filled their truck from the emergency water treatment plant. Of those tested for E.coli, 9, (17%) tested positive. Results of this rapid assessment suggested that tanker water was not reliably chlorinated, and consequently, about one in six trucks delivered water contaminated with E.coli.