Alameda County Water District (ACWD) serves the cities of Fremont, Newark and Union City, California. Commercial, Industrial and Institutional (CII) customers comprise 30% of ACWD customer base. Water efficiency efforts in the CII sector are a part of ACWD's goals related to its Integrated Resource Plan and the Best Management Practices (BMP) in the Memorandum of Understanding (MOU) set forth by the California Water Conservation Council. A pilot program, conducted in 1998, identified the ten most significant CII water user categories, and performed an Industrial Water Use Efficiency (IWUE) at one firm from each of the top five water-using industries. Pilot surveys quantified cost effective measures for each industrial and large institutional customer group. The second phase of the CII program, which took place during 1999-2002, consisted of performing water efficiency surveys at 17 industrial and institutional facilities that had been targeted from the top 25 CII water users in ACWD's service area. The studies identified a variety of opportunities to increase water use efficiency at the plants surveyed. These water use efficiency opportunities included repairing large leaks, eliminating once through cooling, replacing high flow sanitary fixtures and increasing cooling tower efficiency. WUE surveys identified potential CII water savings of 17%, with possible larger reductions if opportunities involving reuse and/or recycling were implemented. WUE surveys also determined the range of water efficiency for cooling towers and reverse osmosis ultra pure water production equipment within the District, and evaluated the relative water efficiency performance of several water conservation, reuse and recycling opportunities already implemented by some District CII customers. This information will be used to recommend future improvements at other plants. This paper provides a case study of one of the participants in ACWD's IWUE program, New United Motors Manufacturing, Inc. (NUMMI), and how they used the information and recommendations in their survey report. NUMMI, a General Motors-Toyota partnership, is the largest U.S. manufacturer of Toyota Corolla cars and Toyota Tacoma trucks. The NUMMI plant sits on 90 acres with a four million square foot facility, employing approximately 5,000 people. The water efficiency efforts at NUMMI are part of a Japanese production method called Kaizen, a system of continuous improvement in finding and eliminating waste. The Kaizen method allowed ACWD to work with NUMMI in addressing four production processes, three of which account for 37% of total facility water use. This paper showcases NUMMI's IWUE survey, Kaizen-assisted water efficiency efforts, and the implementation of recommended system modifications from the IWUE survey. It also looks closely at the dramatic water savings from 1990 through 2003 and how the NUMMI and ACWD partnership reduced NUMMI's water demand from 1,100 gallons per unit to 711 gallons per unit, a 35 percent reduction. Includes tables, figures.