Yeah I have never had water go in the house but saying that if it ever did it would be down to a vent defect, I think there is a topic on here about it.I find that that they put the water exactly where I want it, in a dense, high pressure deluge and mist, fizzing and flushing out amongst the bristles. I also find they flush out the vents without getting too much, if any, water passing through into the house. Very rarely a drop gets in.
But defo the 100 fan jets are amazing and make quick work of any job.
I also use a medium mixed sill brush for all jobs.