21. How do I know the arsenic levels are safe once I've installed a treatment system?

  • Test the treated water one or two weeks after the installation is complete. This is very important. Even the best water treatment professionals can make a mistake and your system may not be working due to an error. DEP staff have seen homes with the wrong media in the tank (pH adjustment media instead of arsenic treatment media). Good installations have been observed to not remove any arsenic for an entire year because of incorrect settings on the bypass valves. Hence the importance of the initial after-installation test.
  • After the initial testing shows the system is working, you should test the water at the kitchen sink and between the worker and the safety tanks (on a POE system) once every year.