So it's best to consider any hose near a pumpout to be unfit for potable water. Where possible, take on fresh water somewhere else. Or go with Greg's solution.

Wherever/however you take on water, be sure to let it run long enough to purge all the water that's been sitting in the dock supply line and any hose connected to it before starting to fill your tank(s)...'cuz hoses sitting in the warm summer sun are incubators for the bacteria, molds, fungi etc that cause water to turn funky. Water from any municipal supply here in the US or in most other developed countries will still be safe, but it's still a PITA to recommission the system more than once a year to get back to water that tastes and smells like anything you'd want to drink or cook with.