Temporary connections are the ones most likely to be missed, because nobody thinks of a hydrant meter or a construction hookup as plumbing.
A water truck filling from a hydrant, a construction site on a temporary service, a food truck, an event connection — all of them attach something unknown to the public main, often with a hose, often without anybody who knows the rules watching. And a tank on a truck is below the hydrant, which makes suction the obvious failure.
Most water providers require backflow protection on any hydrant meter or temporary service for exactly this reason. It is usually the provider's own equipment and their own rule, and it is worth asking about before the connection rather than after.
Which assembly your provider will accept depends on their cross-connection control program and the code in force where you are. The seven device types we see on the Western Slope.
Schedule a backflow test or call 970-835-9661