Is drinking a lot of water first thing in the morning healthy? Is there any science that supports doing it? Seems to me like drinking something like a quart of water would severely dilute stomach acid.
If you're thirsty in the morning, drink some water. If you're still thirsty, drink some more. Most likely, you'll have to pee after a while. This is normal, and you should pee when you get the chance. If you get thirsty again, drink some more water. Lather, rinse, repeat.
It is best to be hydrated at all times, and you're more dehydrated in the morning which is why it's recommended to drink first thing. You only have to worry about diluting stomach acid if you're digesting food. I've heard you should wait about 30 minutes to eat after drinking water, but this is only a rough guideline which doesn't factor in the state of your body and what you're eating. It does not mean that you should be dehydrated when you eat. Remember that your food also contains water. Sipping water with your meal if you are thirsty will not make a significant difference nor impair digestion.