在目前所有饮用水消毒用游离余氯的潜在替代品中，臭氧是最有效的杀菌剂。二氧化氯与次氯酸钠相当，但与游离的余氯相反，当pH值在通常应用消毒的范围内增加时，其效率大大提高。氯胺是比次氯酸盐离子弱的杀生剂，次氯酸盐离子是游离余氯的最低效形式。由于不同微生物和实验条件的效率不同，因此不可能对生物杀灭效率进行精确的定量排序。实验室研究并不总是直接适用于现场消毒剂的使用。 讨论了溶解盐效应、氯氨化和水传播疾病。包括14个参考文献、表格和图表。

Of all the current potential alternatives to free residual chlorine for drinking water disinfection, ozone is the most potent biocide. Chlorine dioxide is about on par with hypochlorous acid, but in contrast to free residual chlorine, its efficiency increases substantially as pH increases in the range at which disinfection is usually applied. Chloramines are weaker biocides than hypochlorite ion, the least efficient form of free residual chlorine. Precise quantitative ranking of biocidal efficiencies is not possible because efficiencies differ with different microorganisms and experimental conditions. Laboratory studies are not always directly applicable to disinfectant use in the field. Dissolved salt effects, chlorammoniation, and waterborne diseases are discussed. Includes 14 references, tables, figures.