Occasionally in winter some inhabitants of the city of Paris complain of a bad chlorinous odour when the chlorine residual in the water distribution network is 0.1 mg/l. Several hypotheses have been made. Many taste and odour profiles have been made on one plant and aminoacids and aldehydes have been analysed. Chlorination of urea has not led to the chlorinous taste. We think that these odours are due to trichloramine, which is produced by chlorination of some organo nitrogen compounds with a slow kinetics of formation during winter. Results show that the combined chlorine level is constant with time and we have reproduced this offensive odour but the origin does not seem to be aldehydes.
Welte, B., & Montiel, A. (1999). Study of the possible origins of chlorinous taste and odour episodes in a distribution network. In Water Science and Technology (Vol. 40, pp. 257–263). https://doi.org/10.1016/S0273-1223(99)00566-1