If you stay at a camp ground or caravan site you can optain water easily at designated locations. But on extended remote trips in foreign countries you often dont have that opportunities. Also travellers who are staying wild don`t have that option.
During my jorneys in europe, africa or south america I mostly was able to get water by asking at gas stations, at a car mechanics or truck service stations at higways at example. When I was more remotely, I did even ask in a farm who near the streets or at a private house.
Also at 5 Star Hotels you often can see someone with a garden hose who is looking for the plants, an easy "drive by" action for us.
Today at 2021 we probably haven`t to be very creative anymore, as long as we have a internet connection. The following directory shows natural water sources world wide.
If you use this Adress on your tablet or smartphone you can see all water sources nearby on a map. You can zoom and click on the different sources.
There you can find and optain drinkable water, but indeed - in severall ways to optain. Just rarely you will find something like a stopcock and probably never an garden hose what you can use to fill your tank. And not all water sources are easily to use if you plan to fill up your 15 Gallon tank, a reason why you probably will have to try 2-3 options for the best access.
If you like to use this options for water refilling you should look for gear to optain the water easily.