If you are new to The Hills here are a list of Utilities that may be helpful for your transition: 

For Water/Sewer/Trash Utilities:
Hurst Creek MUD 
bills all three services together. Visit the website in the link and click " New Service " for the appropriate paperwork to have the services put in your name.
102 Trophy Dr.
The Hills, TX 78738

Electric Utilities: 
Depending on your address in The Hills you will be serviced by either P.E.C. or City of Austin.

Pedernales Electric Cooperative
201 South Avenue F
Johnson City, TX 78636  

Austin Energy / City of Austin Electric Service  
721 Barton Springs Road
Austin, TX 78701