Not all types of dirt actually gets wet as it goes through the water, that's why they put a filter like the Dyson on their E Series vacuums.
You also need to empty the water every time or the bearings will rust and seize up.
Like I said check out the head and tell me what that suction control thing actually does........
Every vacuum out there has some sort of gimmick that really does not make it any better than the next, some fall for it some don't.
I sold quite a few $1600 vacuum cleaners I knew about all of them.
I guess I never returned to this thread back in Dec. and never saw this reply.
There's really no gimmick to the Rainbow, so there's nothing to fall for. The concept of using water in a basin as the filter to trap dirt is not rocket science. Wet dirt can't fly. Dirt is water soluble.
Obviously, however, there *are* some types of materials or matter that might need to be picked up in the vacuum which may not be water soluble. Things such as sanded drywall, sawdust, powder, other things such as that - are not going to be absorbed into the water. That's why they have a special filter. And really, the Rainbow isn't meant to be a "shop vac" type of vacuum. But ordinary household dust & dirt - it's water soluble and the Rainbow has no trouble with that. Wet dust & dirt can't fly. So there's no dust going back into the air.
I've had one for over 20 years. I wouldn't have any other type of cleaner.