Spores of aerobic spore-forming bacteria were used as microbial surrog
ates for evaluating drinking water treatment plant performance. A meth
od for assaying for the microbial surrogate was developed. Various wat
er sources were surveyed, and data were collected from coagulation and
chlorine inactivation studies. Evaluations for spore removals and tur
bidity and particle removals were compared for pilot-scale and full-sc
ale water treatment plants.