Kidney problem because of drinking alcohol and it start to feel pain in the lower back after drinking water what's the reason and what to do in this case?

Stop drinking alcohol and see a nephrologist. We realize that stopping is much easier said than done, but we managed it, and so can you. If you have already damaged your kidneys, your liver can't be far behind. Do you want to live, or not? That is the question you need to consider at this point.