Plastic tastes in drinking water: factors affecting the chemistry of bromophenol formation

A “plastic” or “chemical” taint, has recently emerged as a problem in drinking water in Perth, Western Australia. The taste occurs intermittently in zones receiving blends of treated groundwaters from several sources, generally only in boiled water. The compound primarily responsible is 2,6-dibromophenol (taste threshold concentration 0.5 ng/L). It was established that the relative ratios of phenol, bromide and chlorine, and pH are important determinants in whether the taste would or would not form and that the primary sources of phenol are plastic appliances, especially kettles and refrigerators (Heitz et al., 2001). However, bromophenol formation varied widely between waters from different sources, even though reaction conditions were ostensibly identical, and it was concluded that another, as yet unknown, factor must influence the reaction rate. This could account for observations that plastic taste only occurred in some groundwaters, but not in others. In the present study the effects of organic and inorganic nitrogen-containing compounds on phenol bromination rates were examined, with the view that this might give some insights into the nature of the unknown factor discussed above. These compounds slowed the rate of bromophenol formation, and results suggested that disinfection using chloramine, rather than chlorine, could prevent plastic taste problems.