Regarding the USEPA sampling frequency for radionuclides in drinking water for individual contaminants at each entry point: If results of testing are below the detection limit of an approval method, what is the frequency of sampling?

Regarding the USEPA sampling frequency for radionuclides in drinking water for individual contaminants at each entry point: If results of testing are below the detection limit of an approval method, what is the frequency of sampling?

• A. 3 years
• B. 6 years
• C. 9 years
• D. 12 years

Answer: (C)

The main idea is that monitoring frequency for radionuclides can be reduced when results are not detected. If testing shows results below the method detection limit at each entry point, EPA allows extending the sampling interval to once every 9 years. This reflects a very low chance of exceeding the radionuclide MCL while easing the monitoring burden on the system. If a radionuclide is detected above the detection limit (or an MCL is approached), the sampling frequency would be increased again to a more frequent cycle. Keep in mind that each entry point is evaluated separately, so each can follow the same 9-year interval if non-detectable.

The main idea is that monitoring frequency for radionuclides can be reduced when results are not detected. If testing shows results below the method detection limit at each entry point, EPA allows extending the sampling interval to once every 9 years. This reflects a very low chance of exceeding the radionuclide MCL while easing the monitoring burden on the system. If a radionuclide is detected above the detection limit (or an MCL is approached), the sampling frequency would be increased again to a more frequent cycle. Keep in mind that each entry point is evaluated separately, so each can follow the same 9-year interval if non-detectable.