A method of producing a fuel additive includes: passing a first process stream comprising C4 hydrocarbons through a methyl tertiary butyl ether synthesis unit producing a first recycle stream; passing the first recycle stream through a hydration unit producing the fuel additive and a second recycle stream; passing the second recycle stream through a recycle hydrogenation unit and a deisobutanizer unit; and recycling the second recycle stream to the methyl tertiary butyl ether synthesis unit.