The amount of water that a 70 pound dog should drink per day is around 56 ounces to 60 ounces.
That equals out to around 7 to 8 cups of water per day for the 70 lb dog for the dog to stay properly hydrated.
The best thing to do is just leave out plenty of water that is accessible to the dog at all times and the dog will drink enough water that it needs.
The dog will drink the water when they are thirsty so they do not get dehydrated.
The general rule of thumb when it comes to how much water a dog should drink is that the dog should drink at least 1 ounce of water for each lb of body weight.
So a 70 lb dog may need 70 ounces of water per day but it can depend on how thirsty the dog is and if it's hot out or not.
When the weather is hot the dog may drink more water than they would when it's cooler out.