Work undertaken by Ontario Hydro, Toronto, to determine levels of feedwater impurities, including corrosion products and condenser cooling water inleakage contaminants, is reviewed. Corrosion product measurement using a grab method gave some useful data but was found to be too labor-intensive. Continuous analysis of corrosion products, in conjunction with a valveless capillary sampler, is now being evaluated as a method. Ion chromatography appears to be a promising technique to determine anions in feedwater. Tests to adapt such an instrument for continuous analysis are planned.