The bromide content of underground waters. Part II. Observations on the chlorination of water containing free ammonia and naturally occurring bromide

Abstract In Part I of this paper reference was made to the occurrence of up to 2·20 p.p.m. of bromine, combined as bromide, in some underground water supplies of Southern England. The effect of traces of bromide in tests for free chlorine is now discussed. Bacteriological experiments also indicate that when waters containing free ammonia are being chlorinated, the presence of small amounts of bromide leads to a considerable acceleration of the rate of sterilisation: it appears that this effect is marked with 1 p.p.m. of combined bromine but as little as 0·25 p.p.m. may be significant under some conditions. The experiments were mainly confined to the case where the organic content of the water was very small, but this frequently applies in underground supplies.