Hi guys, I've gotta back up the steve man, as long as you have sufficent pressure (above 60psi or so) then the only 'real' way to boost production is to add membranes or use a higher capacity membrane.
I just had a look at the purewindowwater pictures and let me tell you something - that is a death trap. You cannot properly secure an IBC tank in a van - Intermediate Bulk Carrier, its for transporting fluids on the back of a lorry, where it poses no threat to the driver etc etc, not in the back of a van where it can tear away from its pallet and ....well, I don't need to say any more.