If you'll be camping in a park with "city water," that is, water from a faucet, there's some good accessories to keep in your RV storage compartment. These can make your visit easier--even safer for you rig. Inexpensive, you'll bless yourself for having them when you need them.
Even before you hang the hose on the tap, there are a couple of helpful devices you might need. First, there are situations where the "threads" on the water faucet are stripped, or deliberately not there--to prevent folks from hooking a hose to an otherwise good spigot. Assuming you have the right to the water, a little device known as a "water thief" can help out here.
The 'thief' a rubber sleeve that snugs over a spigot, and at the other end, a brass threaded connection allows your water hose to hook up normally. If you're filling up your tank, just slip the thief on the faucet, hook up your hose, and fill away. If you'll be putting any real pressure on the hose--say hooking it directly to your "city water" inlet on the RV, you'll need to use a hose clamp to snug the rubber sleeve end onto the faucet.
A water pressure regulator can also save you lots of headaches. Typically RVers complain that the pressure they encounter in a campground or RV park is too low, but it only takes one case of over pressurization to blow a fitting in your rig to really make your blood boil. A simple RV water pressure regulator can prevent over pressure from doing real damage. Where do you put it? We've seen plenty of RVers who hook the things between the water hose and the city water inlet on the rig. But why not protect the water hose too? Hook it on the campground faucet, thence to the hose and all your bases are covered. Yes, there is a slight fall-off of water volume when you use this rig, but the peace of mind is usually figured to be worth while. Is it worth the extra money to buy the fancy "adjustable" water pressure regulators? Not from what we've heard. Some say they simply don't work as advertised.
Finally, a fitting you probably do want between the hose and the city water inlet is an entry elbow. If your water hose kinks or bends where it mates up with your water inlet, you can be sure water flow will be impaired, and a premature death of the water hose is likely. For less than $10 you can buy a metal elbow that allows the water hose to hang vertically, rather than cramped.