Do I really need custom water for filter coffee?

[Pastry]

Brewer and filter: Hario V60 02 ceramic; Cafec Abaca 02
Grinder, burr and calibration: KINGrinder K6; 48 mm conical burr; 92 clicks from zero
Bean, roaster, process and roast date: Peru Cajamarca decaf; local specialty roaster; EA decaf; roast date 2026-08-04
Dose and water mass: 20.0 g coffee; 340 g water
Temperature and water profile: 94°C; filtered tap water, about 85 ppm TDS
Pour/agitation schedule: 60 g bloom for 45 s, then two even pours to 340 g; one gentle swirl
Drawdown time: 3:05
Expected and perceived flavour: expected floral sweetness and clear acidity; perceived cup is flatter and drier than expected
Changes already tested: rested the coffee three additional days and repeated the same recipe

I ran this as a small controlled test because my memory is apparently very confident and very bad. Everything except the variable in the title stayed fixed. The difference was larger than I expected.

[Pastry]

That tracks with my experience. The useful part is that you wrote down what stayed fixed, so somebody else can actually test it.

[Typecase]

I am less convinced by the flavour claim than the workflow claim, but that may be because my water is different.

[Philip-BlueNotes]

That tracks with my experience. The useful part is that you wrote down what stayed fixed, so somebody else can actually test it.

[Seed-Saver]

Coffee people will spend forty minutes designing a faster breakfast.

[Cleaver]

That tracks with my experience. The useful part is that you wrote down what stayed fixed, so somebody else can actually test it.

[Warehouse Groove]

I am less convinced by the flavour claim than the workflow claim, but that may be because my water is different.

[Author]

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