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Subject Area: Environmental Management/Environment
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Article citation: Sundeep K. Gupta and Robert Quick, (2006) "Inadequate drinking water quality from tanker trucks following a tsunami disaster, Aceh, Indonesia, June 2005", Disaster Prevention and Management, Vol. 15 Iss: 1, pp. -
To the Editor:
The tsunami that devastated Aceh province, Indonesia on December 26, 2004 destroyed much of the existing water and sanitation infrastructure. Displaced populations living in crowded, unsanitary conditions were consequently at risk of waterborne disease. Abundant local access to water facilitated the early achievement of Sphere minimum standards in disaster response for water supply. However, few data were available to ensure that Sphere Minimum Standards for water quality, i.e. zero E. coli, were being met (The Sphere Project, 2004). A number of organizations engaged tanker trucks to deliver water to affected populations. Many relief organizations assumed that the trucks provided safe water, and some organizations insisted that tanker truck water be promoted as safe to drink (Water and Sanitation Committee, Aceh Provincial Government and UNICEF, 2005). However, no surveillance systems were in place to monitor tanker truck water quality.
Trucks were instructed to fill up with chlorinated water at the only safe water source for the provincial capital of Banda Aceh and surrounding areas: the emergency water treatment plant (EWTP) set up next to the tsunami-damaged Lumbaro water treatment plant (referred to hereafter as the municipal plant). As the number of tanker trucks increased to meet growing demand, the lines of trucks each day at the EWTP grew and waiting times increased to as long as five hours. Some trucks were observed to leave the waiting line and fill at unsafe alternative sources. To determine the extent of this practice and its risk to the population, WHO, CARE International Indonesia, and CDC conducted a rapid assessment of tanker truck water quality.
We conducted a survey of truck drivers waiting in line at the WTP between 8:00 a.m. and 1:00 p.m. from June 3 to 5, 2005. We asked truck drivers about the last place they filled and we collected water samples. We recorded the number of trucks waiting in line at different times and the number of minutes required to fill. Water samples were tested for residual free chlorine levels using a calibrated Hach chlorine pocket colorimeter (Hach Co., Loveland, CO), and for E. coli using the Colilert® method (IDEXX Laboratories, Inc., 2005). We obtained and tested water samples for residual chlorine from the EWTP on June 3 and 4, 2005.
We surveyed 40 tanker trucks operated by 12 organizations. Among 40 trucks, 3 (7.5 percent) had no water to test, 14 (35 percent) were tested once, 10 (25 percent) were tested twice, 11 (27.5 percent) were tested on three occasions, and 2 (5 percent) were tested on four occasions. A total of 75 water samples were collected and tested for residual free chlorine, and of these, 54 were also tested for E. coli.
Of 40 truck drivers, 8 (20 percent) acknowledged filling with unchlorinated water from the municipal plant, 1 (2.5 percent) from a contaminated spring, and 4 (10 percent)
The authors would like to acknowledge the assistance of Erik Norremark and Herlina Sjaifuddin, WHO Aceh, Alicia Gray, Yale University, and Irawati Arsyad, CARE International Indonesia (Aceh) in conducting this evaluation.from undisclosed sources. Observations made at the EWTP every 20 minutes between 8:30 a.m. and 3:30 p.m. on June 4 showed that the median number of trucks waiting in line to fill at one of two filling stations was 22 (range, 10-25). The median fill time of 21 trucks was 15 minutes (range, 5-97 minutes); the median estimated waiting time was 2.75 hours. The EWTP output water had a free chlorine residual of 0.2 mg/l on June 3 and 0.6 mg/l on June 4. Of 75 truck water samples tested for free chlorine, 42 (56.0 percent) had adequate chlorine residuals (greater than or equal to 0.1 mg/l). Of the 33 samples with inadequate chlorine residuals, 27 (81.8 percent) reported having last filled their truck at the EWTP.
Of 54 water samples, 9 (17 percent) tested positive for E. coli. Of these nine samples, four were obtained from trucks that reported having last filled at the municipal plant, three at the EWTP, one at a contaminated spring, and the other at an undisclosed source. Water from the EWTP was less likely to be contaminated with E. coli than water from other sources (9.1 vs 83.3 percent, risk ratio 0.11, p = 0.001).
Results of this rapid assessment suggested that tanker truck water was not reliably chlorinated and, consequently, about one in six trucks delivered water contaminated with E. coli. The extent of this problem was underestimated because only trucks waiting in line at the EWTP were tested, thereby undersampling trucks that were not in line on water testing days because they went directly to alternative water sources. These findings were of particular concern because some organizations in Aceh promoted tanker truck water as safe and resisted attempts to recommend household treatment of this water.
There are three likely contributing factors for these findings. First, long wait times at the WTP induced some truck drivers to fill their tanks with water from unsafe sources. Second, water at the EWTP appeared to be inadequately chlorinated on the two days free chlorine residuals were measured. WHO recommends maintaining a chlorine residual of at least 1.0 mg/l at water treatment plants and 0.2-0.5 mg/l at all points in the water supply system when there is no cholera risk, and 2.0 mg/l at tanker truck filling sites when cholera risk is present (www.who.int/water_sanitation_health/dwq/S13.pdf). Third, water samples from some trucks that were reported to have filled at the EWTP had no detectable chlorine residual which suggested that their tanks had sediment with high chlorine demand. Occasional filling with water from alternative sources could have resulted in accumulated sediments.
Three measures could have mitigated the problem described in this letter: increased production capacity at the WTP or an increase in the number of functioning treatment plants would have decreased waiting times, adequate chlorination at EWTP filling stations (preferably above 1 mg/l) would have helped overcome chlorine demand from sediments in tanker trucks, and regular water quality monitoring for tanker trucks would have detected those trucks that were not delivering adequately chlorinated drinking water. The occurrence of this problem in Aceh, where ample funding by relief organizations was available for water supply, suggests that similar problems may occur in other disaster settings where tanker trucks are deployed and resources are scarcer. To protect the health of populations served by tanker trucks, systems of monitoring the quality of source water used to fill the tankers, and the water delivered by the tankers, should be the standard practice in disaster settings.