Hi, you will not be able to flush out alcohol from your system by drinking lots of water. The only way to get rid of it is by abstinance.
If you drinks lots of water, too quickly, you will flush out much needed salt/electrolytes from your body and you will feel bad.
If you are not eating much and particularly not healthily you won't have much of these essential nutrients in the first place. Flushing them out quickly can be deadly (hence deaths which occur with very low calorie liquid diets with people who don't follow the exact advice on drinking water - either too much or too quickly)
If you are not eating much you are already on a low calorie diet so please ease up on the water. Make sure you are getting all nutrients, vitamins etc and if you are still concerned, it is wise to see your doctor.
Take care.