I was very interested in the systems you referenced. I did a bit of checking and found the patent for the system which seems to be held by Freije #6,325,942 for Easywater -- www.easywater.com
I suspect that the system that VWP uses is a variation of the Freije system and they are licensed to sell it.
Easywater is a member of the Better Business Bureau and has no complaints against it.
On first look, the system looks like voodoo but it does have sound scientific principles that support it. The cost is high but the competitors are zero and I'm sure it cost a bit to develop. I may have to try one of these....