Third Wave Water sells little packets you put into gallons of water to make that water better for coffee brewing. I readily admit this is a tough sell for most people and sounds a bit like snake oil. I also remember when I scoffed when a small white box arrived at my desk with claims of coffee improvement by way of some chalky powder. Having used it for months now, I’d advise you not to scoff (yet, at least).

From a tiny Kickstarter campaign to appearing on Shark Tank to finding approval by some of the best minds in coffee (including the president of one of the best companies in the business), Third Wave Water has had an improbable run. The product itself is a collection of minerals that you’re to dump into a gallon of water, shake said gallon and use for coffee brewing. Minerals in water act as the vehicle to pull flavor compounds from coffee grounds, so having the proper balance of them is paramount to pulling the best flavor. Too few of these minerals and your coffee will be lacking in complex flavor and generally pretty one-noted. Too many minerals and your coffee will be overwhelmingly bitter as well.

It should be noted, it’s recommended to use the packets on either distilled water or “soft” (low mineral count) tap water. You do this because if your tap water is already “hard” you’ll just be making the water worse for coffee brewing. Check the US Geological Survey’s Water Hardness Guide to get an idea, if you’re so inclined.

During Prime Day, these magic packets are only $9, down from $14.

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