Significant levels of potentially carcinogenic
bromate were measured in chlorinated tap drinking water
in Metropolitan Manila, Philippines, using an optimized
ion-chromatographic method. This method can quantify
bromate in water down to 4.5 lg l-1 by employing a
postcolumn reaction with acidic fuchsin and subsequent
spectrophotometric detection. The concentration of bromate
in tap drinking water samples collected from 21
locations in cities and municipalities within the 9-month
study period ranged from 7 to 138 lg l-1
. The average
bromate concentration of all tap drinking water samples
was 66 lg l-1 (n = 567), almost seven times greater than
the current regulatory limit in the country. The levels of
bromate in other water types were also determined to
identify the sources of bromate found in the distribution
lines and to further uncover contaminated sites. The concentration
of bromate in water sourced from two rivers and
two water treatment plants ranged from 15 to 80 and 12 to
101 lg l-1
, respectively. Rainwater did not contribute
bromate in rivers but decreased bromate level by dilution.
Groundwater and wastewater samples showed bromate
concentrations as high as 246 and 342 lg l-1
, respectively.
Bromate presence in tap drinking water can be linked to
pollution in natural water bodies and the practice of using
hypochlorite chemicals in addition to gaseous chlorine for
water disinfection. This study established the levels,
occurrence, and possible sources of bromate in local
drinking water supplies.