How long can a tarantula go without water?

[Allthingsterrarium]

I know tarantulas have superhero fasting capabilities when it comes to food but what about water? I have a small water dish, I'm actually just using he lid of a small yeast jar because he only has a 3 inch leg span and I don't want him to drown, I even have a small rock in there so he can climb out if he gets in trouble. Anyway because of the small size of the dish it can be a little hard to tell how much water is left in it. I check it whenever I feed him which is about twice a week and it was dry recently and I'm trying to check it more often now, I've learned. So for future reference how long can a tarantula go without water, especially at his size which is again about a 3 inch legspan?
If it helps he's a Mexican fireleg (brachypelma boehmei, not smithi) and most likely a male which I requested from the place I ordered him from. Still pretty new to tarantulas and he's my first and only so far. I don't want to make any mistakes.

 

[Entity]

They can go a good while without water, but it should never be a question. They should have water available at all times. If it dries out for a day or so it is no big deal. But i would just keep an eye on it. Also boehmei is not as prone to dehydration as other tropical humidity loving species. Also he will not drown. have @Chubbs show u his avic on the amazon pic.

 

[Allthingsterrarium]

Thanks so much! What a relief. I'll look into the pic you mentioned too