1989年夏天，加利福尼亚州康科德市康特拉科斯塔水区对住宅用水审计项目进行了评估，通过三种估算程序确定了每个账户每天平均加仑（gpd/账户）的节约量:构建的对照组、直接估算和统计建模。据估计，1989年的住宅审计计划在1989年9月至1990年8月期间平均节省了约30个gpd/账户（或6%），因此总共节省了约1000万美元。 这些估算值与1988年在康科德进行的住宅审计项目以及在加利福尼亚州帕萨迪纳和诺瓦托进行的类似审计评估得出的估算值相似。根据审计结果提出了一些建议。包括18个参考文献、表格和图表。

The residential water audit program conducted by the Contra Costa Water District of Concord, California, in the summer of 1989 was evaluated to determine savings as average gallons per day per account (gpd/account) by three estimation procedures: the constructed comparison group, direct estimation, and statistical modeling. The 1989 residential audit program was estimated to have yielded average savings of about 30 gpd/account (or 6 percent) from September 1989 through August 1990, resulting in aggregate savings of about 10 mil. gal. These estimates are similar to those obtained from the residential audit program conducted in Concord in 1988 and from evaluation of similar audits conducted in Pasadena and Novato, California. A number of recommendations were made on the basis of audit findings. Includes 18 references, tables, figure.