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💧 Water hardness: why bread differs by city

The white crust in your kettle is the city's rock. Stirred into flour, those same ions decide whether dough slumps or stands.

5
lessons
~20 min
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🔬 Science
subject
Adults
level
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What you’ll learn

  1. The crust in the kettleTreat hardness as dissolved calcium and magnesium, counted as calcium carbonate, and split temporary kettle-scale hardness from the permanent load boiling will not remove.The white ring is the city's rock. USGS bins the milligrams. LibreTexts explains why a kettle clogs and a granite district's kettle stays clean.
  2. What the ions do to doughGive calcium and magnesium each a dough job from Sehn's farinograph work, and treat minerals as yeast food that becomes a brake when the load is too high.Water is the solvent gluten needs. Calcium drinks more water. Magnesium braces the pull. Yeast drinks the same glass. Chlorine is a separate municipal choice.
  3. The baker's windowUse King Arthur's 100–150 ppm band, name the slack and tight extremes, and remember that hard water is often a little alkaline.Under 50 ppm the dough slumps. Over 200 it tightens and slows. Slightly acid is kinder to yeast. Most potable taps are already usable.
  4. Why the bagel story is backwardsPut NYC's soft Catskill tap and London's chalk tap on the same ruler, and credit craft — not a limestone well — for the New York bagel.DEP: 1.8 gpg, about 31 mg/L, soft. Croton can reach 120. Thames chalk is often 200–300+. The slogan faces the wrong altar.
  5. The tap you actually ownRead a utility hardness number, keep chlorine and softeners in their own boxes, and leave the reader with a dough to feel tomorrow plus an honest open question.The report is local USGS. A softener is a salt swap. Tonight read the milligrams. Tomorrow notice slump versus fight. Nobody has finished splitting rock from baker.

Questions this course answers

USGS treats water hardness as which of these?

USGS: hardness is generally the amount of dissolved calcium and magnesium. Chlorine and cloudy tap water are different municipal facts.

Match each hardness idea to what LibreTexts and USGS actually say it is

LibreTexts splits temporary from permanent. USGS bins the total load. The kettle only settles the temporary share.

Match each metal to what Sehn et al. (2015) measured in wheat dough

Sehn spiked flour with the hardness ions as sulfates. Calcium drank more water. Magnesium braced the pull. Combined, they moved development time.

Complete King Arthur's preferred hardness band for bread

King Arthur: generally, water of medium hardness, about 100 to 150 ppm, is best. Soft is under 50. Hard is over 200.

NYC DEP's citywide average hardness is 1.8 grains per gallon as CaCO₃. About how many mg/L is that? (1 gpg ≈ 17.1 mg/L)

1.8 × 17.1 ≈ 31 mg/L. USGS soft. King Arthur soft. The famous bagel tap is not a mineral spring.

In your own words, why is 'New York bagels are special because of mineral-rich water' facing the wrong altar?

DEP: 1.8 gpg citywide, Catskill/Delaware soft. King Arthur: soft water is sticky and slack. The slogan credits the rock. The baker did the work.

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