A Jug of bad wine is obtained when a player attempts to ferment grapes or Zamorak's grapes and fails, similar to burning food. To ferment grapes, a Cooking level of at least 35 is needed.
A player does not receive any cooking experience when the player's unfermented wine or Zamorak's unfermented wine goes bad. Players can drink the bad wine, but this will temporarily reduce the player's Attack level by 3. Drinking more jugs of bad wine will stack this effect.