Does the color of a tank have any significance?
Our tank colors are used to designate one grade of tank from another (in some cases) or to identify a particular product line. Our standard colors are generally translucent natural or blue for industrial tanks and green or black for water tanks. Our below ground tanks are normally natural, yellow or blue. Tank color in most cases is only cosmetic Do not be misled into thinking that a color increases the life expectancy or UV resistance of a tank.
Source: FAQs - Peabody