The bulkhead fitting is an important component. It provides a fitting that can withstand the pressure of gallons of water trying to exit the barrel through the big hole you're about to cut near the bottom. The fitting also provides a union point for the valve. I used a fitting that fits nicely in a 2" hole, and has a rubber gasket that is compressed against the inside wall of the hole with the poly nut threaded on the fitting from the outside.



The bulkhead fitting uses a left-hand thread for the nut. This allows the bulkhead fitting to stay tight after installation when installing the right-hand thread valve assembly.



The valve assembly consists of a nipple that forms the union between the bulkhead fitting and the valve. The valve used is a 3/4" ball valve. Rather than a pin valve, when fully open, this valve has no obstruction to water flow. It is also allows visible inspection of whether the valve is open or closed simply by observing the position of the handle. It costs a little more, but performance is a big value point for me, so I splurged.



I have also depicted a brass quick-connect coupling in the assembly. I also have one on my hose spigot coming from the house water supply, so I can easily and quickly disconnect the garden hose from the house and attach it to the rain barrel. This coupling is also great for hose ends, to allow for quick changes among nozzles, sprinklers, watering wands, etc. Again, performance is worth the added expense, in my opinion.