WhatвЂ™s the difference between your populous City Water and Fresh Water Fill Ports? Love this particular article? Do us a benefit and strike share! You need to understand how your RVвЂ™s water system works and what equipment you need to keep you save and avoid damaging your camper before you take your first trip to the campground. So letвЂ™s get going. The Way They Work Your hose will screw to the town water slot, .