acktually all fire trucks do not have water. they are for ladders, tools, rescue. fire engines and tankers and quints have water.

and most often it’s between 500-2000 gallons. my fire truck (i am a firefighter) can pull 2000 gallons a minute if i let it. so yeap, hydrants or really fast tanker shuttles it is.

There are plenty of rural fire trucks that have to carry their own water and when that starts to run dry, they already made time for the on-call water haulers to arrive and act like a hydrant for the engine.