A uniform color code and set of marking symbols is adopted. Remember, these marks are your guide to a safe and successful. What Are These Little Colored Flags In My Yard Utility Locator Using white paint, flags, or stakes to designate where you intend to dig before you call 811 is very helpful to utility locating technicians Utility marking colors pink . Gas, oil, steam, petroleum or gaseous materials. Potable, or drinkable, water green: Recommended marking guidelines for underground utilities uniform color code for apwa and cga (ansi z535.1) white proposed excavation pink temporary survey markings red electric power lines, cables, conduit, and lighting cables yellow gas,. Public and private utility companies follow a national council uniform color code. The united kingdom uses a colour code similar to the us for marking underground utilities like water, gas, electric, telephone and cables. Contractors will paint different colours onto the pavement to mark areas with under