If you want to go straight to an authoritative source, check Copper in School Drinking Water (MA Dept of Public Health). My own notes on ESM's water and health implications below.
Copper at ESM - a brief chronology
In February 2017, students showed me “blue water” from a grade 4 classroom. I tested (Lamotte test tab) and found the sample had approx. 40 parts per million copper*. I was concerned when I looked up the EPA standard, which sets 1.3 ppm as the action level for copper. Further tests by me, and later by the City identified a half dozen other locations with levels over the EPA standard.
March - the ESM community was informed of the findings (Courant article here), and for non-compliant taps a flushing protocol was instituted. Taps with very high levels were then shut off and later fitted with filters intended to remove copper.
Dec: I identified 3 taps in a kitchen area with very high (>4 ppm, in one case ~40 ppm) copper levels, and reported this to Ms. Thompson and to the PTA.
January: I tested taps that had been OK'd by the city, and found many with levels apparently over the standard. I also tested taps that had been filtered. These had been initially very high. I found that they were still very high - the filters were of a design ineffective in reducing copper.
Currently (1/11/18): Staff and parents have been informed of recent preliminary test results. Many sinks have been turned off, and for others there is a flushing protocol in place, as well as signage. With these measures, it is fair to conclude that ESM's water is safe for consumption.
What are the potential effects of high copper concentrations in drinking water?
The EPA sets a maximum allowable concentration of 1.3 parts per million for copper in drinking water. What if your water is substantially above that level? It is clear that there are negative (though not usually serious) effects fairly close to the 1.3 ppm standard.
- Human trials are summarized in a WHO report (pages 12-13). These found a lowest observed-adverse-effect-levels (LOAEL) in the range of 4-6 ppm. That is to say: there were significant effects (e.g., nausea, vomiting) for individuals consuming drinking water at 4 ppm.
- In ESM's case, exposure was probably low - most contaminated taps were in classrooms, although a kitchen and staff lounge had very high levels. The risk of illness goes up with the volume, and the copper concentration. You would be unlikely to experience symptoms from an occasional drink of water at 4 ppm. A cup of water at 20 ppm would carry 5 times the risk. A quart of water at 20 ppm would carry 20 times the risk.
- If you had a genetic condition--Wilson's disease--high copper levels could be life threatening (FAQ). This condition is rare. There is only a 1 in 50 chance that a population of 600 would include a Wilson's case.
- There is some evidence of a link between copper in drinking water and Alzheimer's (journal article).
It is unlikely that the issue is the utility's water - MDC reports a maximum copper level of 0.0012 ppm (2016). The cause is almost certainly physical, chemical, or electrical interactions with copper plumbing. In ESM's case, it is difficult (for a non plumber) to ID the problem. But it is notable (and unfortunate) that we have problematic taps in distant locations throughout the building.
How can copper contamination be remediated?
Flushing taps appears (from my data) to be very effective, as long as users are compliant. Simply turning off taps is certainly effective, though inconvenient. There are reverse osmosis filters that would be effective, though they would probably cost a few hundred dollars apiece. The ideal solution would be to eliminate the sources of contamination within the plumbing.
Are there additional problems? What about lead?
Lead contamination would be much scarier problem. The school has been tested in the past, and levels were determined to be safe. It is also important to note that our copper problem is not suggestive of a lead problem. Because copper and lead are not caused by the same water chemistry--they are not generally correlated.
My own colorimetric tests are not definitive and not precise. They work like this: if after adding a reagent the solution is orange, I have <1 ppm. If the solution is pure blue, I estimate >4 ppm. And then I can look at gradations in color. I can also estimate concentrations higher than 4 ppm by making dilutions. How do I know that my results are even in the ball park? I calibrated with know copper standards. And my results were largely confirmed by the City's formal tests.