Join Date: Oct 2009
Location: Northern Nevada
Err... Why not take the pennies to the store and spend them?
Modern pennies are made with only a thin plating of copper over a cheaper metal - zinc, I think. If you're hoping for some dissolved copper in the water, I think it'd be better to use some scraps of copper water pipe.
However, I have to wonder just how much copper is going to get into the water. A lot of older - 100 years or more - houses use copper water pipe, and I'd think that if it dissolved at all, then after a century or so those pipes would be full of holes.