Yeah, let's do it. I assert water will improve your mood with no downsides when dehydrated.

http://www.menshealth.com/health/fastest-way-improve-mood

The parent asked you to compare it to alcoholic drinks, not compare it with lower intake of itself.

from a given level of hydration you can choose to drink more water or drink alcohol. i've covered one of the scenarios. at best both alcohol and water change your mood. of course as we all know what has a desirable mood change and the other doesn't at high consumption levels.

So you twist it to high consumption levels. What about moderate recreational usage as the parent suggested?