Gray tank external overflow?

[PowerStroke]

Last weekend when we were camping my wife was taking a shower and I happened to be outside. I heard some water dripping and I looked under the camper (2015 Whitehawk 23MBH) to see water pouring onto the ground just behind the rear axle on the door side. I immediately went over and opened the gray valve and the water stopped pouring out from wherever it was coming from. I went back inside to check the tank level and it showed 1/3 full. This sort of confused me because on our previous camper 2013 Passport 199ML when the gray tank was full it would just back up into the sink, shower ect.. Any ideas?

[Greydennyhawk]

I have an idea!
Recently, something like that happened to me as I was filling the fresh water tank.
I crawled under and found that the probe that senses 1/3 full had popped out.
( there are actually 3 probes in the tank) and probably 3 each in the grey, and also black tank. So, crawl under and see what you find.
I couldn't put it in by myself, so being under warranty, I drove over to Buffalo RV who repaired it for me immediately, and checked the others for integrity.

[PowerStroke]

I will have to crawl under and look. I can't imagine there would be a vent or anything else down there so something is definitely not right.