The Difficulty of Using Coliphages as “Indicators” and “Index” Organisms

A number of coliphages were concentrated from water by magnesium chloride flocculation and a Virosorb 1MDS filtration method. The effect of adding non-ionic and anionic detergents was also investigated. There were only small differences between the results of flocculation and filtration. Non-ionic detergent had little effect on results but anionic detergent could reduce recoveries. Phage types and water quality influenced recovery as did phage aggregation. Standardization was thus difficult to achieve: this cast doubt on the use of phages as indicator or index organisms except in strictly defined systems.