Won't matter, I think, in an RV. I have had a one inch water hose. It delivers more flow if your water pressure and flow is high enough.
At the time I had a three stage, five hp peak ten, I think pump in the well. It ran ninety pounds of pressure and a lot of flow. The capacitor went bad and no one could find one to replace it. This about the time everything started coming from China.
It was labeled fire hose. Largest I've seen in a while is 3/4 from Costco. It's not the quality i want but it does have machined brass ends.
Water hose for the RV came from Fleet wood store and is 25 ft, 5/8 dia, I think, blue with stainless ends.