EXHIBIT 21 UNITED WATER RESOURCES INC. LIST OF SUBSIDIARIES OF THE REGISTRANT Names of Companies and their Subsidiaries States of Incorporation - ----------------------------------------- ----------------------- United Water New Jersey Inc. New Jersey United Water New York Inc. New York United Waterworks Inc. Delaware United Water Idaho Inc. Idaho United Water Florida Inc. Florida United Water Pennsylvania Inc. Pennsylvania United Water New Rochelle Inc. New York United Water Delaware Inc. Delaware United Water Toms River Inc. New Jersey 14 other subsidiaries in the water services business 7 states United Water Mid-Atlantic Inc. New Jersey Owns 9 subsidiaries in the water services business New Jersey United Properties Group Incorporated New York Owns 7 subsidiaries in the real estate business 3 states United Water UK Limited N/A Laboratory Resources, Inc. New Jersey Twelve (12) other subsidiaries in businesses 4 states related to the water industry or providing services to affiliates