Effectsof Chloramination of Potable Water on the Performance of Materials

ReportNo WSAA 141

July 1998

Thecorrosion resistance and behaviour of materials in water reticulation systemscan be markedly changed by the water chemistry. Total dissolved solids, inparticular chlorides, sulphates, bicarbonates, and pH have the greatestinfluence from a corrosion aspect. But for any given water supply the additionof disinfection agents (which are usually strong oxidising agents) can alsochange the corrosivity of the water. Chlorination is a major disinfectionprocess and its corrosive effects have been widely investigated (Dillon &Yeo, Dillon, Nicholas) and it is known that this accelerates the corrosion ofcopper based alloys. Chloramination is less widely adopted as a method ofdisinfection but its use is increasing. The effects of chloramination onmaterials performance has similarly been less widely investigated particularlywith respect to metallic materials. The original concern with thechloramination process was related to the use of ammonia. Excessive levels ofammonia and/or ammonium ions are known to be very aggressive to copper andcopper based alloys and it was considered that the presence of these compoundscould accelerate the corrosion of these materials which are widely used inwater reticulation systems.

As aresult a testing program was devised to determine the effects of chloraminationon materials commonly used in water reticulation systems. The project consistedof a combination of field and laboratory testing.

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