Portland based Coava Coffee Roasters must be making a killing with their new metal Kone filter for Chemex, and Disk filter for the Aeropress. Both of them seem to be spreading around the world, judging by all the twitter reports and blog coverage. Last week I spent a morning over at Solde Kafferosteri with Dan and Oscar testing out the Disk, and preparing for Oscar’s debut as an international barista competitor in Poland (haha).

Dan from Solde was nice enough to have us over on a Monday morning. The roastery is literally on the wrong side of the tracks, out in the industrial port area of Malmö. We started with a cupping, and then set about the day’s task. Serious, but without any pretensions of scientific rigor, we tried a variety of tests aiming mostly to satisfy our own curiosity about what tastes good. Our main question was the effect of the metal filter on taste, compared to paper.

My personal opinion is that the paper filter tasted too bright and imbalanced compared to the same coffee prepared with the metal filter (using the same grind). With the Disk it tasted more developed, fuller in flavor, with more perceived sweetness.

That said, when the coffee was on the heavier, earthier side (i.e. a Sumatra) I thought the paper filter tasted very slightly better (but not by as big a margin as the lighter coffees prepared with a metal filter). Now, like I said this isn’t a test to end all tests and it really doesn’t prove much, so take it as just one small point of reference. I know that in the past I’ve been happy using paper on the Aeropress, so the next step would be to try comparing different grind settings optimized for each filter…

But I did come to one conclusion, and feel my taste buds somewhat vindicated — when I first arrived in Malmö I felt like the coffee I was brewing at home tasted muted. That set me off on a quest, first, for bottled water – none of which worked well. Then to find a water filter, which, after much searching, I eventually found at a health food store. I guess no one in Sweden buys them, because none of the big stores stock them. And the cashiers look at you funny if you ask about water filters. This is Sweden, only quacks (and coffee geeks) filter their tap water.

But at our little cupping, sure enough the difference was noticeable. Brewing with tap water is like tasting coffee with cottonballs in your mouth. So… buy a water filter if you brew coffee at home.

UPDATE: Coava has split into two companies: Coava the roastery and cafe, and Able Brewing, which handles the production of coffee gear. The Able Brewing / Coava disk filter can be purchased on Amazon, as Able Brewing’s site is still under construction at the moment. A third revision to the disk filter is coming out later this year, so keep an eye out for that.

Full disclosure: We paid for the Disk filters, international shipping and all. And I have no financial interest in the Swedish water filter industry. This is not a conspiracy. Though, if I could secretly make a fortune by recommending filtered water to Swedes, that’d be awesome.