Construction of Nonpotable Water Systems
40 CFR 142.62 – Construction of nonpotable water systems or systems carrying any other nonpotable substance must prevent backflow or backsiphonage into a potable water system. The purpose of this requirement is to protect the facility water supply (i.e. well or off-site system from backflow of operational water). A device installed to prevent backflow can be accomplished with fixed-air gaps, break tanks, Reduced Pressure Zone (RPZ) valves or multiple back check valves installed in series.
Sanitation
29 CFR 1910.141(b)(2)(ii) – Outlets for nonpotable water, such as water for industrial or firefighting purposes, must be posted or otherwise marked in a manner that will indicate clearly that the water is unsafe and is not to be used for drinking, washing of the person, cooking, washing of food, washing of cooking or eating utensils, washing of food preparation or processing premises, or personal service rooms, or for washing clothes.