AKA the plastic-jug vodka taste challenge
In 1949, it was mandated by the Bureau of Alcohol, Tobacco, & Firearms that vodka be "neutral spirits without distinctive character, aroma, taste, or color". Although this hard liquor is a recent recipient of the attentions of the regulators, the Twentieth Century was, in many ways, the Century of Vodka. One might say that, through the efforts of Madison Avenue, Ronald conquered communism, but vodka conquered America. The results of this advertising war, from which either Sweden or Russia will claim the title of Vodkaland, remain unclear, but sales of vodka have surpassed those of whiskey and gin. The market share that vodka has captured developed premium vodkas such as Skyy and Grey Goose. Vodka has become the hard alcohol of choice for many, due to its clear taste.
But sometimes cheap vodka has an off-taste: metallic, oily, plastine, or just plain gross. This is particularly true of plastic jug vodka. Here is a procedure an old college friend of mine recently developed. I have tasted the difference several times, and have used it successfully to adjust and improve the flavor of plastic jug vodka, and can recommend it heartily. Remove the reservoir (top half) of a britta waterfilter from its pitcher and place in a large glass jar, so that the outflow will run into said jar. Pour the plastic jug vodka through the filter. Store the resultant filtered vodka in clean glass for careful drinking later.