A Note on the Break-point Chlorination of Swimming Bath Water and of Urine

(County Afialyst’s Deportment, Mat lock, Derbyshite) Other workersl havc reported unusual results for combined chlorine in swimming bath water. Thc signiflcant features ofthese results have been the stability and high concentration of what appeared to be dichloramine, in the prcscnce of free chlorine and at a pH at rhich dichloramine is accepted as being unstable.’ Similar results have bee. obtained on samples of swimming bath u,ater examined in this department. The method of analysis was that given in “Approved Methods for the Physical and Chemical Examination of Water”, Third Edition, 1960, page 38. Table I gives representativc results on some samples recently examined. The last three columns give results conventionally as chlorine, monochloramine and dichloramine. lt is by no means certain that these are the con-rpoulds mcasured. 139 TABLE ] Chlorine MonochloramineSample B C D E F pH 69 ‘7.1 8.3 5 8.35 8.0 7.55 1.42 020 0.60 0.30 0.20 1.3 3 014 080 0.07 0.06 0.08 0.16 Dichloramine 0.50 1.44 0.18 0.18 0.1’7 0.21 Some of these samples were treated with incrcasing doses of chlorine but a normal break-point curve was not obtained.