Softened water usually bypasses the faucet used for drinking water because it adds a LOT of salt to replace the undersirable minerals. Your best bet is demineralised water or revers osmosis.
If your asking where one might purchase the trivet alone, I think Chemex sells them directly from their website. Other than that, my only guess would be to try Kitchen Capers at a shopping mall near you. Oh wait! There's Fantes. http://www.fantes.com/trivets.html and here is the Chemex site http://www.chemexcoffeemaker.com/products/accessories.html hope that helps (sorry too for the delay, I've been out of town and very busy.)
