The sensitivity and specificity of a pooled E. coli conjugate specific for enteropathogenic E. coli types, and of a conjugate specific for E. coli O groups frequently associated with urinary tract infections was studied. This demonstrated that FA tests using these conjugates were not suitable for the detection of E. coli in routine water examination. The highest overall rate of positive FA reactions with E. coli strains isolated from water was 38.4%. This figure was considered to be well below that desirable to enable the FA tests to be used as an alternative to conventional cultural methods for the detection of E. coli.