I also have a pair of the Scepter 20L cans. But, I find them inconvenient for anything other than water storage. I prefer something I can place on my tailgate and dispense from a spigot. I always carry a jug with a spigot, and when I need more than 5 gallons I refill as necessary from the Scepters. Trying to pour water in a pot or bottle is a PITA from the Scepter cans.
I use mine for pouring into pans, cups, etc. I just don't open the vent on the lid and unscrew the ~1" cap, it sorta 'glugs' out but works ok. There was a thread on ExPo? about a spigot mod for the Scepter cap, allowing you to simply tip the can on its side and open the valve, that might be a great solution to the issue.