本文讨论了成本分配的基本额外容量法的原理和原理，并说明了其对确定服务阻塞率成本的影响。住宅、商业和工业用户用水的典型特征用于演示适用于各类用户的服务成本费率设计。这种成本分配方法允许设计公平的递减区块费率，该费率将根据适用于所有客户的单一单位成本，收回适用于每个客户类别的服务成本。包括表格，如图所示。

This article discusses the principles and philosophy of the baseextra capacity method of cost allocation and illustrates its effect on determining cost-of-service block rates. Typical characteristics of water usage for residential, commercial, and industrial customers are used to demonstrate the design of cost-of-service rates applicable to each class of customer. This method of cost allocation permits design of equitable declining block rates that will recover the costs of service applicable to each customer class based on a single set of unit costs applicable to all customers. Includes tables, figure.