On average, the liver takes one hour to metabolize one ounce of alcohol. For most people, one ounce of alcohol will produce a .015 blood-alcohol concentration. This means someone with a .015 blood-alcohol level will have little to no alcohol in their bloodstream after 10 hours have passed. So the more you drink, the longer alcohol stays in the system. Liver metabolism rates also affect how alcohol will make you feel if you continue to keep drinking.