Silver coin in a water bottle. Does it keep stuff from growing?

[doubleganger]

I can report from my own experience that a coil of heavy uninsulated copper wire will keep algae from growing in a birdbath.

 

[lambertiana]

Copper sulfate is widely used to knock down algal blooms in reservoirs. Metallic copper has antimicrobial properties, and silver is even better. But I don't know if it would work for treating a bottle of water.

 

[Wasty]

Well, old thread, but nowadays quite useful...
Lots of metals kill germs, its called the oligodynamic effect.
For further info just take a look at the wikpedia article: https://en.wikipedia.org/wiki/Oligodynamic_effect

That is the reason for brass doorknobs and handles in some hospitals...