A circular copper tube with an inner diameter of 2 cm and a length of 100 m is used to transport drinking water. Water flows in the tube at an average velocity of 0.11 m/s at 20C. At the inner tube surface, the mass concentration of copper in water is 50 g/m3 . The Environmental Protection Agency (EPA) sets the standards for the National Primary Drinking Water Regulations (NPDWR) that apply to public water systems. The drinking water regulations limit the levels of contaminants in drinking water to protect public health. The maximum contaminant level for copper in drinking water, set by the NPDWR, is 1.3 mg/L. Above that, additional steps are required to treat the water before it is considered safe for the public. Determine whether the water from the tube has a safe level of copper as per the NPDWR. The diffusion coefficient for copper in water is 1.5 109 m2 /s