There are many companies that operate in the public utilities field, ranging from large multinational corporations to small regional providers. These companies are involved in various aspects of the industry, including generation, transmission, distribution, and retailing of electricity, gas, and water. Here are some of the companies in the public utilities field:

• American Water Works Company, Inc.
• Duke Energy
• Dominion Energy
• Southern Company
• American Electric Power
• AES Corporation
• Edison International
• Pinnacle West Capital Corporation
• National Grid plc.
• AT&T
• AECOM
• Anglian Water
• BP
• Centrica
• Chevron
• E.ON
• EDF Energy
• ExxonMobil

Note that this is not an exhaustive list, and there are many other companies that operate in the public utilities field. Some of these companies operate across multiple states and serve millions of customers, while others serve specific regions or communities and may specialize in a particular type of service, such as renewable energy or water treatment.