Although the quality of water in Scotland is generally very good, bacteria can pose a risk to human health via shellfish, bathing and drinking water quality issues. Faecal indicator organisms are of primary concern, since they are the key microbial water quality compliance parameters – specifically, Escherichia coli and intestinal enterococci under the revised Bathing Waters Directive and Shellfish Waters Directive. These bacteria, which are generally non-pathogenic, are excreted by all warm-blooded animals and their presence indicates an environmental pathway contaminated with faecal waste which may be contributed to by a pathogen carrier(s).

The aim of this work is to design an effective faecal indicator organism screening methodology for Scotland that could be developed quickly and at a reasonable cost, that will enable, within acceptable limits:

1. Prediction of current faecal indicator organism loadings (ideally concentration & flow) being delivered to specific receptor waters under different flow conditions and in different seasons  
2. Source apportionment of overall FIO loadings to sources within catchments
3. Estimation of ‘zone of influence’ of individual sources within catchments
4. Estimation of impacts of interventions to reduce fluxes from sewerage- and/or agricultural-related sources.