An evaluation of two bacteriophages as sewage tracers

The suitability as sewage tracers of two bacteriophages, a Staphylococcus aureus phage and a coliphage, was investigated, in terms of background concentrations in a range of effluents and survival in frozen samples. The S. aureus phage appeared to be a suitable tracer for both raw and treated sewage, but the suitability of the coliphage, other than with secondary treated effluent, was more doubtful. Concentrations of both phages in frozen samples were reduced by 90 per cent in 2 days, but over the next 68 days decreased more slowly to about 5 per cent. In a field evaluation, the two phages were used together to trace the movement of oxidation pond effluents in a river.