Cal-OSHA does, indeed require cool (below ambient temperature) water on the site, 2 gal. per worker, or a quart per hour. If potable water is available at the site, you can replenish it as needed, but you need to carry a hose with whatever vehicle carries the water around. I used to keep a 5-foot drinking-water-suitable hose wrapped around one of the five-gallon coolers. I had an entire crew get pretty sick from drinking from a garden hose that was left under pressure lying in a homeowner's yard. You'd be amazed at how many nasty bugs will grow in the hose when you do that, hence the need for the short hose certified for drinking water. They sell these at home improvement centers, etc. for use with campers. Water that's heavily iced down can induce shock that can give you instant stomach cramps or knock you out cold if you guzzle it. Better to keep ice in a seperate cooler, and throw a little in the drink coolers once in awhile.
I've switched to buying the bottled water when it's on sale. I get 24-packs for $2 and sometimes 32-packs two for $4 all the time, at dollar stores, farm stores, you name it. I've never found either the 5-gallon coolers or the bottled water to be much of an inconvenience or expense. It's nothing compared to the inconvenience and expense of heat exhaustion and a crew that's dragging ass because they're dehydrated and don't realize it. I not only encourage, but insist, that anyone working with us takes frequent drink breaks. Production has always been better when nobody is cranky, woozy or worn out from working in the heat while dehydrated.
If OSHA insisted that everyone wears a pink tutu and silver ballerina slippers at work, I'd agree that was over-regulation. Personally, I've never met a regulator who wasn't just doing his job and trying to get employers to care about their employees. Maybe there's a big, evil OSHA guy out there who just wants to drive around all day and make up stupid **** for people to do that doesn't mean anything... but I've never met him. I've met an awful lot of people who spend half the day whining about the government in an air conditioned vehicle or bar or coffeeshop, while they left a crew of eight guys working their ***** off on a hot roof five stories up, with no water or gatorade and making **** wages. Oddly enough, they're usually bitching that they can't keep workers, either. Big surprise, there.
I think that anyone who can figure out how to get a construction job completed successfully, can probably figure out how to keep the crew healthy and happy while they're at it. I don't think that's an unreasonable expectation, myself.