Trihalomethane formation in whirlpool SPAs

In a survey of 25 whirlpool spas using halogen disinfectants, the only organohalide contaminant observed in the water and in the air at concentrations in excess of 1 μg l⁻¹ (water) and 1 μg m⁻³ (air) was the trihalomethane corresponding to the disinfectant used. The levels of trihalomethane observed in the water in thermal spas were comparable to levels reported for swimming pools. We conclude that the heat, agitation and aeration of the spas do not produce higher residual levels of trihalomethanes in the water and do not promote the formation of novel volatile organohalides. The concentration of trihalomethane in the water appeared to be related to the combination of high total dissolved solids and high disinfectant levels. The trihalomethane levels in the air though dependent on the concentration of trihalomethane in the water were modified by the variety of room sizes, ventilation rates, water surface areas and aeration rates associated with each individual spa.