在这篇文章中，作者报告了最近爆发的水传播疾病，如霍乱和伤寒。这些暴发中的每一次都可归因于缺乏过滤或过程的错误操作和维护。本文介绍了中试工厂数据和全规模运行的结果，以说明各种形式的过滤在将微生物种群减少到易于通过消毒控制的浓度方面的有效性。慢砂滤器、快速砂滤器和硅藻土（DE）滤器相对于其去除大肠菌群、减少总显微镜计数、去除病毒和去除贾第虫囊肿的能力进行了讨论。 如果设计和操作得当，这三种过滤器都能去除细菌、病毒和囊肿。作者提醒，操作人员应认识到过滤器的脆弱性，尤其是在反洗后30分钟至1小时内，过滤器去除细菌、病毒和囊肿的效率降低。包括25个参考文献、表格和图表。

In this article, the authors report on recent outbreaks of waterborne diseases such as cholera and typhoid fever. Each one of these outbreaks can be attributed to the lack of filtration or to faulty operation and maintenance of the process. Pilot plant data and results from full-scale operation are presented to illustrate the effectiveness of various forms of filtration in reducing microbial populations to concentrations that are easily controlled by disinfection. Slow sand filters, rapid sand filters, and diatomaceous earth (DE) filters are discussed relative to their ability to remove coliforms, reduce total microscopic count, remove viruses, and remove Giardia cysts. All three filters are capable of removing bacteria, viruses, and cysts if designed and operated properly. The authors caution that operators should recognize the vulnerability of filters, especially their lowered efficiency for removing bacteria, virus, and cysts, in the 30 minutes to one hour after backwashing. Includes 25 references, tables, figures.