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On September 3, 1991, the Edwards Underground Water District (EUWD) received a completed application form from the Bexar Metropolitan Water District (BMWD) requesting a leak detection/location survey on its water distribution system. A pre-survey conference was held January 9, 1991 at the BMWD main office to discuss the work to be performed. It was agreed that EUWD would perform sonic leak detection on all available access points, computerized leak location as needed, record any unusual system conditions found, and submit to the utility an updated master water plat with the final report.

Mark L. McGinnis and John E. Gapinski of EUWD began the survey on February 10, 1992, and the survey was concluded on January 8, 1993. Over the course of the survey, EUWD surveyed a total of 37,716 access points including 30,270 customer service connections, 2,066 fire hydrants, 5,257 valves, and 123 other access points covering 421.37 miles of distribution mains. Computer leak sound correlation was performed on 17 locations by EUWD and numerous other locations by BMWD personnel.

EUWD technicians detected a total of 1,907 leaks. This total included 354 meter box leaks, 143 fire hydrant leaks, 44 service leaks, 21 main line leaks, 19 main valve leaks, and 1,326 customer side leaks. EUWD estimates 547,596 gallons of water per day has been saved by the repair of 375 detected leaks as of January 8, 1993. Additionally, 165 leaks were repaired without leakage estimates. The leaks discovered during the survey range from 129,600 gallons per day to numerous small meter box leaks.

As part of the survey, EUWD located 417 service connections, 60 service valves, 19 main valves, 17 fire hydrants, and 5 blow offs with valves not shown on the master water plats. EUWD staff were unable to locate 1,251 service connections and 799 valves shown on the master water plats. An additional 1,404 valve stacks need cleaning and/or repair and 90 valve and meter box lids were discovered missing.