We have come across a few occasions where, because of the action of previous travellers (and sometimes because of certain local residents) , shops and servos have either disabled their outside taps or put a sign up warning not to use the water. When asked they say they have had travellers leave the taps running and just wasting the water, or just expecting to be able to attach their hose and help themselves. (And some do not want to attract certain local residents to set up camp.)
On Bruny Island, Tasmania, they have to buy their drinking water, so the businesses there are a bit touchy. One hotel would not allow any water to be taken and one shop charged for the water, which was fair enough, although they were a bit rude about it. I think it was only $2 for 20 litres, so it was not a problem. We did find a park where there was a tap and we also used that.
At Halls Creek in the Kimberley the only place to get water was at a community centre and only when they are open. The servo would not allow any water to be taken.
But we have always been able to get water from somewhere. We carry two 20 litres containers of drinking water in the camper, 65 litres in the camper’s tank that we do not use for drinking, and as a last resort we have a 20 litre drinking water in the rear of our 4by. We have only had to use it once.
We have also used creek water for washing and depending on the quality, for drinking. (Liffey Falls in Tasmania was a brilliant free camp and the creek water there was perfect for drinking.)
The secret is to always fill up when you can! Kevin