Hi. I was just wondering if... if I drink water for 30 days but still eat regularly will I lose weight and feel better. My mom wanted to see if I could do it

You can't go wrong with water, it has many benefits, hydration, flushing the kidneys, cutting out soft drinks and substituting water helps to control calories.
And in your case (GERD) to help maintain bowel function, this will benefit you greatly.

Drink an 8 oz. glass of water before you eat something. Avoid anything with flour and/or sugar in it.

If you are drinking soda, sugar drinks, yes drinking water instead will help. But also what type of diet and food are you eating, even drinking water will not help that much if you are eating greasy foods, high calorie and more. I