Charcoal filtering removes organic impurities from cheaper varieties of whiskey, bourbon and vodka whilst leaving the alcohol content of the spirit intact. Premium Tennessee whiskeys have already been charcoal-filtered before they are laid down in barrels using the Lincoln County Process. This process, also known as leaching, dates from the 19th century and was used by early spirits rectifiers to improve the taste of their products. Home-made charcoal filters can be assembled using kit readily available at hardware shops and large supermarkets.
Attach one end of a 15 cm (6 inch) length of polycarbonate tubing to the tap of the plastic container tap and the other end to the filter input.
Attach another 15 cm (6 inch) length of polycarbonate tubing to the output side of the cylindrical irrigation filter. Attach the other end of the tube to the glass container which will capture the filtered alcohol.
Unscrew the bottom cap of the cylinder and place two coffee filter papers in the bottom. This will act as a carbon filter. Screw the bottom cap back on.
Unscrew the top cap and half-fill the cylinder with finishing carbon, placing one filter paper inside the cylinder and fill the remainder with activated charcoal up to 3 mm (1/8 inch) of the top. Make sure that the thread is clean and replace the screw top.
If using pre-used glass containers to capture filtered alcohol, ensure that these are sterile by passing boiling water through them before use.
All alcohol should be consumed legally and in a responsible manner.