" Can you image the waste if people paid a fixed charge for water, electricity & gas regardless of consumption?"
Um...You said 'tap' instead of 'forcet' which implies you are in the UK - yet you still don't know that the majority of properties here have unmetered water supplies?
In my 40+ years, every property I have lived at in the UK has had a fixed water charge, and funnily enough I've never left taps on for no good reason!
Similarly, I won't leave live video streaming running on my unmetered internet connection if I'm not using it.
If you think about it, I'm sure you'll find many things you don't waste even when cost isn't a factor.