Over the years I have found that most people come up with a stereotype – down and out, drinks in the morning, can't hold a job, and can't function in the world. In actuality, this describes a very small percentage of people who meet medical criteria for alcohol dependence. A good many of people who are dependent on alcohol are able to hold jobs, own homes, and function in the world. The term "functional alcoholic " best describes this kind of alcoholic.

A functional alcoholic rarely misses work, has very little legal consequences, has plenty of friends and family, and for the most part, looks like an average person functioning in society.
Usually with a functional alcoholic, it is friends and family who suffer the consequences of their drinking. The functional alcoholic may look functional to the outside world but when they are at home they will exhibit less than desirable behaviors that make for problematic relationships. Functional alcoholics are more likely to break promises, be irritable and angry, not follow through on projects, blame and criticize others, have other addictive behaviors, sleep more, avoid conflict and many other behaviors, subtle and not so subtle. The problem with the functional alcoholic is their own internal denial system because they don't look and act like the stereotypical alcoholic.
Here is the truth about functional alcoholics. The functional alcoholic consumes as much alcohol as any "full-blown" alcoholic, they just don't exhibit the outward symptoms of intoxication. This is because they have developed a tolerance for alcohol to the point that it takes more for them to feel the effects (including hangovers). Consequently, they must drink increasingly larger amounts to get the same "buzz" they want.
This slow build-up of alcohol tolerance means the functional alcoholic is drinking at dangerous levels that can result in alcohol-related organ damage, cognitive impairment and alcohol dependence.
The way you can tell if you are a functional alcoholic is to either compare your drinking to those who don't drink much or ask your friends and family if you drink too much. If they say "yes" and you can see what they are seeing then you may be a functional alcoholic. Another way to tell if you are drinking too much is to ask yourself if you have a child, "Would I want my child in adulthood to drink as much as I am?" This kind of question gets pass the denial and identifies your true values.