本文讨论了美国环境保护局（USEPA）的一项提案，该提案旨在修改其如何确定小型供水系统是否能够遵守新的饮用水法规，从而使各州更容易批准小型系统差异（SSV）。美国环保局在制定修订后的方法时考虑了三个关键因素，包括:家庭用水成本的可变性 治疗 小系统支付能力的可变性；和 需要在各级改进执行情况 《安全饮用水法案》（SDWA）中SSV条款的联邦级别。根据一种新的渐进式方法，美国环保局将 考虑每个新规则的可承受性。 它自己的，反对一个低得多的家庭 每个尺码类别的收入门槛。在下面 这种循序渐进的方法是累积的 家庭用水账单将不予考虑， 实际上，取消了2.5%的家庭收入中值（MHI）上限 家庭总成本。美国环保局也在考虑是否 应严格按照成本标准评估可承受性 国家一级使用增量 方法或使用两步流程 此外，还评估了县级的负担能力 当国家级评估显示 监管必须是可承受的。避开潜在的问题 能够识别成本较高的SSV技术 低于可承受性阈值的金额 美国环保局建议考虑技术 “价格合理”，前提是价格比最低的便宜 昂贵的法规遵从性技术和 保护公众健康。"

This article discusses a U.S. Environmental Protection Agency (USEPA) proposal to revise how it determines whether small water systems can afford to comply with new drinking water regulations, thus making it easier for States to grant small system variances (SSVs). The USEPA considered three key factors in developing the revised approach that include: variability in household costs of water treatment; variability in small system ability to pay; and, the need for improved implementation at the federal level of SSV provisions in the Safe Drinking Water Act (SDWA). Under a new incremental approach, the USEPA would consider the affordability of each new rule, on its own, against a much lower household income threshold for each size category. Under this incremental approach, cumulative household water bills would not be considered, in effect removing the 2.5% median household income (MHI) ceiling on total household cost. The USEPA is also considering whether it should evaluate affordability strictly on a national level using the incremental methodology or use a two-step process that additionally assesses county-level affordability when a national-level evaluation shows a regulation to be affordable. To get around the potential problem of not being able to identify SSV technologies that cost less than the affordability threshold amount, the USEPA proposes to consider technologies affordable "if they are cheaper than the least expensive compliance technology and still protective of public health."