Join Date: Jun 2016
Location: Orange County, CA
Chassis: Crown Supercoach II (rear engine)
Engine: Detroit 6V92TAC, DDEC 2, Jake brake, Allison HT740
Rated Cap: 37,400 lbs GVWR
Yes, you do need a vent for the fresh tank, but it doesn't have to be as big as the waste tanks' vents - it just needs to equalize pressure when filling and emptying. I use a 1/2" hose from a 1/2" fitting in the top of each fresh tank, and these hoses come down to ground level. When water begins to squirt out of it, I know that tank is full. Easy!