first of all, I recommend you stop using the CA Water Blade to dry your car. It is a long, straight gouge waiting to happen. It doesn't itself scratch the paint, but dislodge one little piece of grit you didn't get when washing, and you'll be sorry. I saw this happen in front of my own eyes on my black car. Lots has been written about this on the forum.
second, you didn't say why you were claying - but it should NOT be part of your regular regimen. Claying can and will induce swirl marks. Claying is GREAT for getting rid of "above-surface defects" such as adhered road grime, tar, tree sap, bug poop. I've found I only need to clay once every year or two, because I keep the car well waxed and the adhered stuff comes off easily in the course of a regular wash.
Now to answer your question - perfectly OK to leave the rinse water on the car - however I would recommend using car-wash-soapy water. Water alone is a poor lubricant. Soapy water is fine, as is detail spray. If the clay ever grabs or smears on the car, you don't have enough lubricant.