Sunfish.
Calfire have fixed bases so I assume that they have installed water systems. From experience of refuelling a B747, we could load 140 tonnes in 30 minutes or less so I reckon probably at least that for a B747 water tanker as there are no filtering requirements for water. So much less time for a smaller aircraft
I've seen video of a temporary bladder system where the whole system operates on compressed air. The bladder is filled by local pumpers and a compressor coupled up for the aircraft reload.That system has been used in the US for a very long time.
Wunwing