Indiana State Parks, all... have a fill station if there is not water on each site. Those parks that do not have water on each site will have a spigot in a common area for everyone to use.
Sometimes these spigots have a drinking fountain and a threaded spigot. If you have enough hose with you, you can attach a hose and string it to your camper, fill the tank, but then unhook it from the spigot when done. Others need to use this also. Tent campers will fill their jugs and buckets from there. You do not want to put a Y on it and run a dedicated hose to your camper. They are not meant for that purpose. They are a shared spigot.
Other State Parks may have common spigots, but the spigot is not threaded. The first time I came across this, I ended up cutting the end of a hose off and was able to shove the cut end over the outlet (my own homemade "water thief"). The faucet was spring loaded, so I had to stand there, hold the hose on so pressure would not blow it off and hold the faucet handle on at the same time. Water ran slow, and after about 40 minutes my water tank in the camper was filled.
If you are camping at any Indiana State Park or State Recreation area, go to the DNR web site and bring up the Park you are considering. Go to the campground map, select your site. In the description, it will give you the number of feet to the closest water source. Then just make sure you have enough hose to reach. (and a water thief, or a cut off hose you can use for one). I carry 200 feet of hose with me all the time. I've used it all too a few times. But it was well worth it.