I bought the carpet expert. You HAVE to use their cleaning solution. The water reservoir holds about 40 oz The dirty water is full when half full You cannot run back over to suck up more water. You cannot control it. My carpet is SOAKED. It is not user friendly. Prepare to spend half your time learning to use it. Then after it just blinks at you with error messages straight out of the box:two blinking lights: bad. Figure out what the hell two blinking lights mean. This is going back. I have never hated a carpet cleaner like this. It’s the worst one I ever bought and everyone is saying it’s the best somehow.