1.1 本试验方法涵盖了一个程序，用于测试膜过滤器对直径等于或略大于额定孔径为0.40至0.45μm的膜过滤器的细菌的截留能力。 1.2 所述程序用于用户实验室，与制造商实验室不同。 1.3 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.4 本标准并非旨在解决与其使用相关的所有安全问题（如有）。 本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.5 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 使用膜过滤的微生物水质测试程序的前提是，使用的膜过滤器将保留特定尺寸范围内的所有细菌。如果膜过滤器没有保留这些细菌，可能会出现假阴性结果或密度估计值降低，这可能会由于被测水中存在未识别的潜在健康危害而产生严重后果，尤其是在饮用水中。 5. 2. 设计的该程序将使用户能够测试每个膜过滤器批号是否能够保留等于或大于所述膜孔径的所有细菌。

1.1 This test method covers a procedure to test membrane filters for their ability to retain bacteria whose diameter is equal to or slightly larger than membrane filters with pore size rated at 0.40 to 0.45 μm. 1.2 The procedures described are for the use of user laboratories as differentiated from manufacturers’ laboratories. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Microbiological water testing procedures using membrane filtration are based on the premise that all bacteria within a specific size range will be retained by the membrane filter used. If the membrane filter does not retain these bacteria, false negative results or lowered density estimates may occur that could have serious repercussions due to the presence of unrecognized potential health hazards in the water being tested, especially in drinking water. 5.2 This procedure as devised will enable the user to test each membrane filter lot number for its ability to retain all bacteria equal to, or larger than, the stated membrane pore size.