Drinking water rarely exceeds 0.
1 parts per million (ppm), deemed a safe level for wilson's disease
. Testing is not so much for fear of exceeding 0.1ppm, but to make sure your home/school is not prone to excessive leaching (example: acidic water in copper
pipes). Consistent levels <0.1ppm mean leaching is unlikely. Flushing copper pipes (let water run) is recommended before drinking/cooking.
Answer assisted by Aaron Stupple, Medical Student