Check out my custom built trolley, it's up for grabs if any ones interested.
I'ts powered by a car/leisure battery, 
has a 75 psi pump with a flow valve fitted 
and can easily hold about 35 litres. (1+1/5 barrels)
If anyones interested just drop me an email with a sensible offer, 
oh and i've got a spare di filter that i'll chuck in with it.
Im not needing it anymore as i've just installed a tank in my van!
Here's a few pics.   
woodliff@btinternet.com