Brewing Beer with Oshkosh Water

If you make beer, it's important to know your water. In Oshkosh, we have good water for brewing. It has its limitations, but nothing you can't work with.

Here are three years of Oshkosh water reports focusing on properties important to brewers. The water tested was drawn in different parts of the city, at different times of the year.

The good news is that Oshkosh water is consistent. That makes things easier if you plan to adjust your water for brewing. Then there’s the bad news. Certain styles of beer don’t pair well with our water. If you aim to brew something pale and hoppy, you’re likely to struggle if you don’t adjust your water.

Oshkosh water is taken from Lake Winnebago. Like most surface water, ours has fairly low mineral content and fairly high alkalinity. Water like this works best for beers that are darker, maltier, and less bitter. I’ve tasted evidence of that.

Years ago, I joined the Society of Oshkosh Brewers. At meetings, members pass around beers they've made. Early on, I noticed that Oshkosh brewers excelled when it came to darker, malt-driven beers: stouts, porters, ambers. I wasn’t the only one struck by this.

Steve Rehfeldt moved to Oshkosh from Colorado in 1995. He promptly joined the SOBs. Shortly after, he became club president. Rehfeldt liked the SOBs' beers. He noted that “The Oshkosh folks brewed a lot of lagers and malty, dark ales. The beer they were making retained the influence of the Oshkosh brewers who preceded them."

What Rehfeldt says makes perfect sense when you consider our water. Those types of beers are what our water does best. That's not saying you can't brew pale, hoppy beers with Oshkosh water. It's just that you'll need to make adjustments if you hope to make consistently good beer. It's not too difficult. Here's what I do.

Let's say I'm brewing a pre-Prohibition style pilsner. This is a pale lager carrying about 40 IBUs. For this beer, I'll dilute my Oshkosh tap water with 40% distilled water. That helps reduce alkalinity. Then I'll add 1/2 to 3/4 teaspoon of calcium chloride for every five gallons of brewing water. That helps compensate for mineral loss from the dilution. In the mash, I'll use acidulated malt to lower PH. The acidulated malt makes up 3-4% of the total grain bill. If you don't like acidulated malt, 1/2 teaspoon of lactic acid added to the mash would work equally well.

And that's it. There are other ways to do it. But this is simple and it works for me. I don't screw around with it much anymore. Obsessing about water is not my idea of fun. My idea of fun is more boring than that. For example...

Here's an insanely detailed water report from the Oshkosh Brewing Company. This is from 1958. The water was drawn from the brewery's own well. Some of the numbers are off the charts.

Click to enlarge

How did they deal with that? I'm not entirely sure. There's some decent evidence that OBC boiled its water before brewing with it. That’s an old trick for reducing hardness and alkalinity. That would have been a mandatory requirement for a brewery producing a pale, hop-forward lager as its flagship brand.

This stuff goes way back. Brewers in Oshkosh have been tampering with the local water for years. Back in the 1890s, Lorenz Kuenzl at the Gambrinus Brewery was doing it. Kuenzl was trained to brew in Bohemia. One of his specialties was a Bohemian-style pilsner. An 1893 inventory from his brewery shows Kuenzl kept an arsenal of organic acids on hand. Just the stuff for adjusting his water to produce his “celebrated” pale lager.

Of course, you could forget all this bunk and go au naturel. Stick with brewing beers that run from amber to dark and are malt-driven. You’re living in the right place for it. It’s the sort of beer Oshkosh was built on