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The thing that actually removes hardness. Needs a drain. Illegal in some sewer districts. Tagged Amazon listing — check the current page, and size from grains, not bathroom count.
Category
aesthetic
EPA status
No EPA primary MCL. USGS classes water as soft (0–60 mg/L as CaCO3), moderately hard (61–120), hard (121–180), and very hard (more than 180).
Typical sources
Dissolution of carbonate minerals in soil and rock; common in groundwater and in Southwestern surface-water blends.
What actually fits
Some links are affiliate links. If you buy through one, we may earn a commission. That does not change the match, and it is not a medical claim.
As an Amazon Associate we earn from qualifying purchases.
Hardness is the amount of dissolved calcium and magnesium, usually expressed as mg/L (ppm) as calcium carbonate or as grains per gallon (1 gpg ≈ 17.1 mg/L). USGS describes the household effects: soap scum, spots on glass, and scale in water heaters and pipes. USGS also notes that hardness is not a health concern in that description, and that drinking water can contribute dietary calcium and magnesium.
City starting points on this site: Phoenix publishes 10–17.6 gpg. The hard water hub lists every file that already prints a hardness row or a hard/varies class. Santa Clarita Valley prints three hardness columns, not a blended citywide number.
If the tap also stains orange or smells like sulfur, hardness is not the only file. Open iron and sulfur.
Cities on file
Only numbers and notes already printed on a city Markdown file. We do not invent a detection to fill this list.
Highest cited numbers
Only values already printed on a utility report. Sort is the optional numeric field, not a new lab result.