数千个小型水系统由于一个或多个原因不符合地表水处理规则（SWTR）。预计这些小社区的管理当局将节约社区有限的资金，同时为居民提供安全饮用水。在许多情况下，解决办法是延长合规期限，并希望居民在此期间不会生病。本文将描述两个小型社区如何使用硅藻土（D.E.）过滤解决其遵守SWTR的问题。D.E.过滤是一种经过验证和批准的方法，具有以下优点:初始安装和持续成本低；操作简单； 无需混凝或絮凝；最低空间要求；去除1微米以下的固体，包括去除贾第虫和隐孢子虫；无反冲洗；可与预处理（如活性炭或臭氧）结合使用，用于需要减少颜色、气味或三卤甲烷的特殊情况。

Thousands of small water systems are not in compliance with the Surface Water Treatment Rule (SWTR) for one or more reasons. The governing authorities in these small communities are expected to conserve the limited funds of the community and at the same time provide the residents with safe drinking water. In many cases the solution has been to gain extensions of compliance deadlines and to hope that residents do not get sick in the interim. This paper will describe how two small communities solved their problems of compliance with the SWTR, using diatomaceous earth (D.E.) filtration. D.E. filtration is a proven and approved method that offers the following advantages: low initial installation and ongoing cost; simplicity of operation; no coagulation or flocculation required; minimum space requirements; removal of solids down to one micron, including giardia and cryptosporidium removal; no backwashing; and can be used in conjunction with a pretreatment, such as activated carbon or ozone, for special cases requiring color, odor or trihalomethane reduction.