Matt Mika wrote:
I have a porcelin/metal sink that I'd like to put an extra hole in for
a R/O water dispenser. Can these things be drilled? Or do I need to
get a new sink?

Thanks,
Matt Mika

I did mine by grinding the porcelain off with a Dremel tool, then
drilling the cast iron.

Be sure to grind *ALL* the porcelain off where the hole will go.
I left just a smidgeon and drilling took out a big chip. Luckily
the added faucet (for filtered water) covered it.

- good luck -