According to the Texas Commission on Environmental Authority (TCEQ) code 30 TAC 290.44(h)(1) requires backflow prevention on all connections to a public water system that may present a hazard or potential hazard. The acceptable backflow prevention device for a hose bib is an AVB pictured below in the illustrations.
The potential hazards with a hose bib/garden hose can be many. One common hazard is any chemical attached to a hose (pictured below).
Make sure all outside faucets are protected by an AVB, which can be purchased for several dollars at your local hardware store.
Please contact the City of Kerrville Public Works Department with any questions. (830) 257-8000