I would think that depends. In Indonesia a lot of people do just that and seem ok (though lots of hacking and coughing), and in Jordan I saw construction worker

I would think that depends. In Indonesia a lot of people do just that and seem ok (though lots of hacking and coughing), and in Jordan I saw construction workers toiling in the sun all day who wouldn't drink water while fasting, which seemed dangerous to me. The Bedouins I met in Wadi Rum were more lax, saying while traveling or working, they are allowed to eat and drink even during Ramadan, as a matter of a practicality...being in the desert and all.