Is there a law that the employer is required to provide some sort of water on job site? I work 8 hours a day in the sun and the my boss won't get us any water, and if he does he leaves it and expects us to drink the same dirty water for like a week, week and a half.

There is no labor law that makes such a provision. My suggestion is that you contact OSHA to see if such a provision exists under their guidelines.

Is there a law that the employer is required to provide some sort of water on job site? I work 8 hours a day in the sun and the my boss won't get us any water, and if he does he leaves it and expects us to drink the same dirty water for like a week, week and a half.

Yuck. That's a really stupid decision on your employer's part as when someone keels over from dehydration or heat stroke, then it's a worker's compensation claim.

While I'm not aware of any specific regulation to provide water or access to safe drinking water, this could fall under OSHA's "general duty" clause that requires employers to provide a safe workplace. Additionally, if the boss you refer to is not THE boss, you might want to contact someone in higher management and explain the problem.

Can you bring your own water?

From OSHA's General Industry Standard

29 CFR 1910.141(b)(1)(i)
Potable water shall be provided in all places of employment, for drinking, washing of the person, cooking, washing of foods, washing of cooking or eating utensils, washing of food preparation or processing premises, and personal service rooms.