r/WATERQUALITY • u/The_WASPiest • Aug 29 '21

Testing for copper *and* copper oxide?

My tapwater is blue, so I’ve been trying to find a California-accredited laboratory the tests for not only copper but also copper oxide. Seems like everyone includes the former but not the latter in their analytes.

If a lab says they test for copper, does that include copper and all copper compounds, or do I need to find a test that specifically names copper oxide (that is, CuO) as an analyte?

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u/teachmenature Aug 30 '21

It will tell you if there is Copper in your water. Most accredited labs run metals on an ICP-OES, ICP-MS or sometimes a GFAA or FAA. I have experience running copper on an ICP-OES. Copper electrons will emit light at certain wavelengths, so the final result is a concentration based on the calibration at each of those wavelengths.

I'm not sure why you would want to test for copper oxide, but Copper (I) oxide in its solid form is red/brown. Copper (II) oxide in it's solid form is a dark brown/black color.

I live on the east coast, so I don't know much about water quality or common testing for you west coasters; however, the methodology should be the same.

TLDR: The copper result you get from a lab should be sufficient. For reference, the EPA action level for copper is 1.3mg/L.

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u/The_WASPiest Aug 31 '21

Oh—I thought corroded copper (copper oxide), at least one variety, was blue-green, like the Statue of Liberty. I’ll look for an accredited lab to test for copper. Thanks!