It depends. DP- are for rentals which often includes loss of rental income, HO- are for homeowners. Almost all US policies exclude flooding, which is a special insurance. There’s also umbrella insurance for special situations beyond personal or homeowners insurance.

For anything broken that can’t be fixed or replaced to the original value, he should seek a diminished value claim.

Comparision matrix of coverage amongst standard plans:

http://www.andersonmurison.com/personal/coverage%20compariso...

IANALOIA

It’s not up to the homeowner to use his insurance to repair his house when the city did the damage.

I'm not sure why not. Seems like exactly the sort of unlikely event that I'd want my insurance to cover. Isn't the whole point of insurance that they make me whole, and use their ample legal department to pursue the responsible parties to recover those costs (if such parties exist, in this case the city)?

Your insurance is there only to protect you, not to protect others that cause damages to you.