Although drinking 8 cups of water per day is a good starting point for most adults, one size (or 8 cups) does not fit all!
In fact, staying well hydrated depends on several factors. First of all the quality of water is at least as important (if not more) as the quantity of water we drink. Please do not take water quality for granted, and that includes both bottled water and tap water, whether filtered or not.
There are many other factors, such as the type of beverages you drink, the water content of the foods you eat, intake of diuretic herbs, alcohol, medicines, your body weight, your activity level, and also the weather! For example, hot weather increases water loss from your body due to sweating or perspiration, and your water intake needs to increase accordingly, particularly for outdoor activities in hot weather.
Hydration is so important that it is worth your time to dig deeper into this “8 cups of water” topic. Please see this blog post for more details.