When you puke, you get rid of the alcohol in your stomach. However, if the alcohol is already in your system, puking won't help.

If your body is continuing to make you puke, you've probably poisoned yourself. Your body is desperately trying to get rid of the toxic substance killing you, but it's too late to eject it out through the mouth, so it just has to tank the damage by sacrificing liver cells and brain cells, which are both things your body Does Not Like.

If you're still drinking after your body triggered its poison response, well, it's trying to stop you from poisoning yourself.

If you regularly drink until you puke, something may be wrong with you medically (making you sick after one or two glasses of alcohol) or you're killing yourself (by drinking way too much alcohol). Either way, you need to get yourself help.

Given your "it becomes like I drink water", I think you have a serious problem.