There's been some recent discussion about approximating Tim Wendleboe's Oslo water, and I had a hard time googling out some reliable numbers. Once I did a google translate of https://www.oslo.kommune.no/vann-og-avl ... skvalitet/ I came across some trustworthy data:



Translating that to more familiar units we have:

Oset
total hardness: 34 - 41 mg/L CaCO₃ equivalent
calcium hardness: 33 - 41 mg/L CaCO₃ equivalent
alkalinity: 25 - 32 mg/L CaCO₃ equivalent
and conductivity of 10 mS/m would read about 50 ppm on an inexpensive (NaCl calibrated) TDS meter

Skullerud
total hardness: 40 - 50 mg/L CaCO₃ equivalent
calcium hardness: 40 - 50 mg/L CaCO₃ equivalent
alkalinity: 30 - 35 mg/L CaCO₃ equivalent
and conductivity of 11.8 mS/m would read about 59 ppm on an inexpensive (NaCl calibrated) TDS meter

Note that these have a non-carbonate hardness in the neighborhood of 10 mg/L CaCO3 equivalent. That would indicate as much as 7.1 mg/L of chloride ion if it were all chloride, or as much as 9.6 mg/L sulfate ion if it were all sulfate.

To approximate the 40:30 hardness:alkalinity values with a Barista Hustle two-bottle recipe you would use about 40 ml of the Mg solution and 30 ml of the buffer solution. Of course it's not quite the same because Oslo is all calcium and BH is all magnesium, and the BH would have about 38 mg/L of sulfate ion.

P.S.
The above numbers are also in rough agreement with what was reported here: https://www.kaffebox.no/june-kaffebox-tim-wendelboe/

Thanks, Pat.
[EDIT: question withdrawn]

Note - I recently got a PM from user, Acavia, who contacted Tim Wendelboe and corroborated that he is using simple charcoal filtered Oslo tap water, and provided a link to an Oslo water quality summary report for 2021 - https://www.oslo.kommune.no/getfile.php ... 202021.pdf

That summary report indicates a total hardness of 2.3 °dH (41 ppm as CaCO3) and alkalinity of 0.64 mmol/L (32 ppm as CaCO3) - pretty much in the middle of the numbers for the two Oslo sources in the first post of this thread.


Edit addition 2023: Someone on the Espresso Aficionado Discord server recently posted a link implying that they may have used osmosis filtration sometime in the past, explaining that it would remove parasites that were in the Oslo tap water for a time. See https://timwendelboe.no/2019/12/vann-og ... nd-coffee/ . The whole archive is dated Dec 2019, but I think the archive post was from October 2007 when Oslo was under a boil water notice.

I have heard that this water is good but have not used it yet(