They don't leak at all. Not much tightening is needed. I put a bead of high quality silicone sealant around the gasket of the bulkhead on the side that contacts the inside of the cooler, pop it through the hole & tighten the nut as hard as I can with my hand. Then give it a quarter turn with pliers, wipe the excess around the fitting & let dry over night. The system is expensive to create, but the reward is unmatched to anything else. The system is very efficient, very easy to operate & most importantly very easy to clean. Its a whole game changer.