You are correct. Some states even require a double check or even an RPZ for an attached irrigation system. As long as check valves are placed after the pressure tank, the underground line from the tank to the wellhead will remain under positive pressure.
In other states like Nebraska, it is mandatory to have a check valve before the pressure tank. Not only does this create a possible contamination problem for the well, but it also causes water hammer on pump start.
I don’t even want to get started on some of the dumb rules in other states like Texas. You just as well beat your head against a wall as try to make sense out of some of them. I think most are politically motivated. If you own a check valve company, and you have enough money to pay the right people, you can get laws past that require a check valve every 20 feet.
The federal government is just as bad. The EPA recently changed the allowable amount of things like arsenic in water from 50 ppb to 10 ppb. So water systems with as little as 13 ppb are getting shut down and are required to spend millions of dollars to reduce the arsenic content. The difference between 10 and 13 ppb is only like 3 drops of water in an entire swimming pool. It is just a scare tactic. “We are the government, and we are here to protect you form the evil corporations and greedy water suppliers.”
What we really need is someone to protect us from government incompetence and over regulations. Wouldn’t it be nice if our government officials had at least seen a pump or water system before they started making rules? It is easy to dupe inspectors because they have no idea what they are looking at. You could have a dozen real safety violations and all the Nebraska inspector would care about is that you have that extra check valve which is actually causing a safety problem.
No place to quit. See I told you I shouldn’t have gotten started.