Effects of Chloramination of Potable Water on the Performance of Materials

This report was produced for the Urban Water Research Association of Australia, a now discontinued research program.

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Report no. UWRAA 141

July 1998

SYNOPSIS

The corrosion resistance and behaviour of materials in water reticulation systems can be markedly changed by the water chemistry. Total dissolved solids, in particular chlorides, sulphates, bicarbonates, and pH have the greatest influence from a corrosion aspect. But for any given water supply the addition of disinfection agents (which are usually strong oxidising agents) can also change the corrosivity of the water. Chlorination is a major disinfection process and its corrosive effects have been widely investigated (Dillon &Yeo, Dillon, Nicholas) and it is known that this accelerates the corrosion of copper based alloys.

Chloramination is less widely adopted as a method of disinfection but its use is increasing. The effects of chloramination on materials performance has similarly been less widely investigated particularly with respect to metallic materials. The original concern with the chloramination process was related to the use of ammonia. Excessive levels of ammonia and/or ammonium ions are known to be very aggressive to copper and copper based alloys and it was considered that the presence of these compounds could accelerate the corrosion of these materials which are widely used in water reticulation systems.

As a result a testing program was devised to determine the effects of chloramination on materials commonly used in water reticulation systems. The project consisted of a combination of field and laboratory testing.

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