A process for the conversion of tertiary butyl alcohol to ethyl tertiary butyl ether, including: dehydrating tertiary butyl alcohol to form a product stream comprising isobutylene and water; separating the product stream to form an isobutylene-rich fraction and a water-rich fraction; separating the water-rich fraction to recover a hydrocarbon fraction and a water fraction having less than 1 ppm hydrocarbon content; reacting isobutylene in the isobutylene-rich fraction with ethanol to form a reaction product comprising ethyl tertiary butyl ether; separating the reaction product to recover unreacted ethanol and an ethyl tertiary butyl ether stream; and recycling at least a portion of the unreacted ethanol to the reacting; wherein the ethyl tertiary butyl ether stream comprises at least 99 weight percent ethyl tertiary butyl ether.