Why this is the single costliest thing families miss
A denied water or fire claim on a house found unoccupied without notice can run into five figures, and "I didn't know about the clause" doesn't change the outcome at claim time. The exact clause wording varies by insurer, which is why the call to yours is the first item on the checklist.
What to actually say on the call
"The house at [address] is now unoccupied. What does my policy require, and can I have that in writing?" Ask specifically how many days unoccupied changes coverage, whether a vacancy endorsement is available, and what it costs.
What doesn't need to disconnect just because a house is empty
Heat and hydro should stay on, not get shut off to save money — disconnecting usually breaches the same vacancy condition being protected, and refilling a drained heating system after a freeze costs more than the utility bill ever would have.