My yard irrigation is run off a shallow well which gives about 5 to 7 gpm when all is going well. The problem is that the well runs dry in the summer. Many alternatives have been tried, shorter runs and longer recovery periods, which do help but it does run dry.
How can the well be coupled in with city water (city water is not cheap - hence the well) to kick in when the well starts losing pressure but still if and when the well recovers, revert back to the well water.
The driver here is I am an RV'r; and when we travel I would like to maintain my lawn and shrubs without the concern that the pump is going to burn out.
Is there a ' buy it from Home Depot' type solution or will it involve a custom setup?
Having thought about it for some time I have accepted it is beyond my ability to solve.
Help would be wonderful

How can the well be coupled in with city water You can't! Every plumbing code in the United States prohibits commingling city water with ANYTHINMG. You can get in BIG trouble for that. My area waters their lawns with sprinkler systems fed by shallow well pumps. I have one myself. I don't know how long you've had your well or how deep it is but I do know that as the area builds up and there's more draw on the water table it falls. And that's what yours has done.
Your only solution. IMO, would be to have the well drove deeper. Good luck, Tom