[mwbridgwater]

We have a counter-top water purification system consisting of two stages of filtering in stainless steel canisters ("Berkey").  After a couple of years, we had an incident of some kind of bacterial (?) growth inside, cleaned everything, came back....  Anyway, I'm wondering about suspending a copper bar inside each of the stainless steel sections, as copper is well known to kill bacteria, virus, mold, fungus.

My question is concerning the galvanic corrosion which would occur between the two metals.  Copper and stainless steel are far enough apart on the scale to be reactive with each other.  Copper dissolved into the drinking water is very desirable from a health standpoint, whereas the elements in stainless steel can be toxic.  Copper is on the annodic end of the two, so it seems to me that the copper would degrade and travel to the stainless steel - presenting no problem and perhaps even enhancing the solution of copper in the water.  A glass vessel system would have been perfect instead, but it is what it is...

Any thoughts?

[Borek]

Copper dissolved into the drinking water is very desirable from a health standpoint

Quite the opposite, copper is highly toxic, as most heavy metals are.

[incorporealist]

Given that you need free copper ions (preferably Cu(I)) to act as an antimicrobial, if galvanic action were to occur it may accomplish your goal. You would need to test the water for concentrations to ensure you aren't above the toxicity limits.

Copper dissolved into the drinking water is very desirable from a health standpoint

Quite the opposite, copper is highly toxic, as most heavy metals are.

Copper isn't considered toxic until it reaches ≈1.3-3.0 mg/L.
https://www.ncbi.nlm.nih.gov/books/NBK225399/

Similarly, small amounts of copper are indeed beneficial to one's health so long as your body is metabolizing it properly.
https://www.who.int/water_sanitation_health/dwq/chemicals/copper.pdf

[billnotgatez]

...
You would need to test the water for concentrations to ensure you aren't above the toxicity limits.
...

There is no mention of monitoring in the original post.
We can not assume they will be able to do monitoring in a safe manner.