Alcohol affects all individuals on a different level. Alcohol can remain in ones system for up to 24 hours after a drinking session. The length of time alcohol is detected within ones system is determined by the BAC level within the body.An individual with a BAC of 0.10% can pass alcohol through their system quickly, being detected only up to 8 hours.lcohol affects all individuals on a different level. Alcohol can remain in ones system for up to 24 hours after a drinking session. The length of time alcohol is detected within ones system is determined by the BAC level within the body.