Are we talking 1 operative which is vital in relation to the question .
Just myself as i work on my own 300 ltrs maybe a little more when my flat tank hits the point were i cant get anymore water out parked on a level road their will still be 75 ltrs or so left in tank .
I use 1mm pencil jets (clarkes 1mm welding tips) so have a lower setting current setting in cold weather is 26 and have a 3-4ft jet of water . Mike