I went down the sack barrow with the barrels on at first , now using a surflow backpack strapped to the sackbarrow . they are about £170 ish . it comes with it's own surflow 4 speed pump and battery.
I keep it on the trolly all the time and just fill it up from the containers , It has a big cap on it , I can fill it up quicker than it took me to change over a barrel before .
I'll post a pic later .
on the first speed setting i can do a 4 bed house with 3/4 of the fill ( about 15ltrs )