Most notable is a study of 20,000 Seventh-Day Adventists, who were followed for six years to look for impact of fluid intake on mortality. The researchers found that drinking more water lowered the risk of dying. For women, the risk was lowered by having three or more cups per day, versus fewer than three. For men, three to four cups was much better than fewer than three, and five or more cups was a bit better than that. And at least one study has found that more than six cups of water a day lowers bladder cancer risk relative to less than one cup.
One gallon is about 128 ounces, so if one tea bag is good for 10 oz  of water, then about 10 teabags is good for a gallon. Start with 10  and adjust accordingly with water. 4 people found this useful.
1 Gallon [UK] = 18.18436 Cups [Metric]. For other volume unit conversions, please go to Volume Conversion. Fluid and dry gallons to cups conversion factors are listed below. To find out how many cups in gallons, multiply by the factor or instead, use the converter below for fluid gallons. 1 Gallon [Fluid, US] = 16 Cups [US]. For cup to gallon converter, please go to cup to gallon. Converter. Enter a US fluid gallon value that you want to convert into cups and click on the convert button. Gallon is an imperial and U.S. customary unit. There is one type of gallon in imperial system and 2 types (liquid and dry) in united states customary system.