If he's drinking 6 glasses of the drink or more a day, the one cup would be sufficient, For general good health for anybody, it is recommended that we drink half our weight in ounces of water a day. It can be in other forms coffee, tea,etc.
So if your husband weighs 160 lbs, he would need 80 oz. or water a day. Water is also filling, so if he wants only 6 glasses lemonaid mixture he can drink extra water if hungry.Best to both of you as you strive for better health.