1986年9月至1988年5月，对一个运行缓慢的砂水过滤装置进行了研究，以确定其从水源水中去除贾第虫和隐孢子虫的效率。有限的量化数据表明，过滤设备平均去除了93%的贾第虫囊肿，35个未过滤水样中只有一个检测到这种原生动物。平均48%的隐孢子虫卵囊被切除。46%的过滤样本中检测到隐孢子虫。这些发现表明，在非常寒冷的操作条件下，或者如果过滤装置不符合公认的设计标准，隐孢子虫可能无法从受污染的水源水中充分去除。 其他变量包括浊度、总大肠菌群和粪便大肠菌群。包括40个参考文献和表格。

Between September 1986 and May 1988 a study of an operating slow sand water filtration plant was undertaken to determine its efficiency in removing Giardia and Cryptosporidium from a source water. The limited quantified data demonstrated an average 93 percent removal of Giardia cysts by the filtration plant, with this protozoan being detected in only one of 35 unfiltered water samples. An average 48 percent of Cryptosporidium oocysts was removed. Cryptosporidium was detected in 46 percent of the filtered samples. These findings suggest that Cryptosporidium may not be adequately removed from a contaminated source water under very cold operating conditions or if the filtration plant does not comply with accepted design standards. Other variables were turbidity and total and fecal coliform bacteria. Includes 40 references, tables.