Sunseeker 2016 Drip from Blue Pex

I have read some of the post on this, but not sure if they apply to our set up. Behind the passenger side tire there are two pex pipes one is Red with a cap and there is a blue without a cap. There is water dripping from the blue pipe. I have read in the forum that it is an over follow pipe. we have a little under 1/2 a tank of fresh water. So I can not figure out why it is dripping. The only place I see a possible connection is above the pipe by the passenger side rear wheel is the water pump. The is a thumb (?) valve that is parallel to the hose so it is off. Can't figure why it is dripping? Also when I dewinterized I did open that that valve to drain the water antifreeze then closed it. So Im at a loss as to stopping the drip.

Thanks