I’d be very careful about using copper this way. While ingesting small amounts of copper is ok, and in fact a good part of a diet, Ingesting too much copper is not a good thing, and can be toxic.

Having copper piping, etc. in close proximity to a garden risks having it leach into the plants, which might then be ingested. Since copper is a fairly soft metal then rain could slowly corrode it and introduce it to the plants.

A bit more on copper toxicology here.