we will be staying in A loop with a camper, are there outdoor water faucets available to fill our camper holding tank or do have to fill at home and carry water there.

They have fill stations on the way out but at the actual site is electric only.

You can get water at the outdoor sinks at the bathrooms. We've stayed there multiple times. Be sure to hike the Sundew Trail!

According to recreation.gov loop A has electric only loop B has water and electric. It's a beautiful place large sites. Checkout the co-op in Winter Harbor for the lobster and take a boat ride to Bar Harbor.

Unfortunately, there's only electric at each site.