While a good rule of thumb is .24L per 5lbs of dog (for dogs under 20lbs); large, active dogs in hot weather can easily consume .03L of water per pound of body weight, meaning a 75lb dog can drink 2.25L of water a day.
Ultimately, the amount of water a dog drinks depends on their age, weight, breed, diet, and energy level. You know your dog better than any scientific calculation, but a good place to start is with a calculator.
We found this dog hydration calculator online. Check it out and tell us, does it seem accurate to you?
Finally, if you are headed out on an adventure that requires bringing your own hydration, know the capacity of your dog’s pack and your dog’s estimated consumption ahead of time. Our SingleTrak Pack™, created for short duration adventures, holds a combined 1L of water, while our multi-day backpacking pack, the Palisades Pack™, holds a combined 2L. We recommend adding additional water bladders if more water is needed.