Calm down B & T...
I see where you are coming from, but perhaps a little extreme?
FF2: It's been difficult in recent circumstances to keep everything on the aircraft working perfectly. For example, each night we got back to base recently the toilets had to be dropped and the water tanks emptied, along with all relevant CB's pulled. Even then, there is residual water in the systems which freezes and causes problems.
First flight of the day, if the water bowsers haven't frozen then we refill the tanks and turn all the heaters on. Even then, I have had to take off with a still frozen system, knowing it should defrost shortly.
I don't know the Dash or your sector, but perhaps it could have been a first flight of the day? Also, without checking the MEL, it may be possible to despatch without water. As B & T was alluding to, we often spend longer in areas without access to water than maybe a short sector on a Dash?
We also carry hand sanitisers, so we would provide that plus bottled water if we have a potable water problem.
DW.