What's Changed? CARB vs. Non-CARB
The evolution from the fast-flowing, messy jugs of the past to a more controlled, slower-flowing product is largely in response to the California Air Resources Board (CARB). Their 1999 adoption of regulations to control the amount of smog-forming gases that escape from ordinary fuel containers set the standard for jerry jug design in California.
CARB established requirements for five-gallon and smaller portable fueling devices (containers larger than 5-gallons are exempt) to curb vaporous emissions. In the process of addressing the release of fumes through the nozzles, vents and even the plastic sidewalls of the jugs, new features also targeted the leaks of fluid contents through better nozzle design. Features of new CARB-compliant jerry jugs include a single opening for pouring and venting, treated polyethylene plastic for low permeation, and an auto shut-off, self venting nozzle which springs closed when not pouring.
Currently, the following states have adopted CARB requirements and retailers may only sell CARB-compliant jerry jugs: CA, CT, DC, DE, ME, MD, NH, NJ, NY, OH, PA, TX, and VA. Eventually, you may not be able to purchase anything but CARB-compliant jugs, as the EPA estimates nationwide compliance by 2009.