This is all a bit simplistic, wfp and who designed it is a bit wider.Many of the advances made in water purification came about in the seventies and were said to be space race spin offs.
Remember for what we do to work, leisure batteries, pumps, and smaller bore hose all had to be developed, not to mention the internal combustion engine to drag it all round, and suspensions that could take the large weights involved.
If Ionics had the first van mount system maybe they can be said to have invented it in it's current form
Much of the widespread adoption in later years has had to do with h&s legislation.Only in the last few years have sensible domestic polls been available. The slx is pretty much cutting edge along with the gardiners superlite brush.
So wfp is pretty much a work in progress, and we are all able to chip bits in.