i do have one or two ideas, but i think its realy just as fast pouring it into the tank from the containers, its a complaint i see a lot on the forums.they are scared the water spilling down into the wiring near the battery may damage it, or its a pain lifting containers all day
this was an idea i had its very simple but efective just using gravity.
what you can do is this, buy containers like this with a tap and connect
a piece of hose about a metre. put the container on its side turn on the tap and the water comes flying out into the other container.you would need to have it slightly higher than the other container that you are going to refill.just a quick idea jouk45
you put the hose on the end of the tap by means of a pipe clip, and simply turn the tap to release the water,
this container has a venting cap at the back, so the air is pushing the water out faster.
even better, if you make a shelf on the side of the van slightly tilting down, enough for two container, you can join the containers by means of air coupling. this way the water transfers to the bottom as it gets empty,a constant flow. they just click into one another and you get no leaks.
this one goes into the bottom of the leading container.
this one goes into the lid. jouk45