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Water Hardness Guide

Water hardness measures dissolved calcium and magnesium, expressed in milligrams per litre of calcium carbonate (mg/L CaCO₃). Hard water isn't a health risk — in fact, the WHO notes that hard water can contribute meaningfully to daily calcium and magnesium intake. The number mostly tells you about taste, mouthfeel, and how a water behaves with soap, tea, and coffee.

Classification

Soft

0 – 60 mg/L

Light mouthfeel, brews tea cleanly.

Moderately hard

60 – 120 mg/L

Balanced; the everyday sweet spot.

Hard

120 – 180 mg/L

Distinct mineral character, fuller body.

Very hard

180+ mg/L

Strong mineral taste; significant Ca/Mg contribution.

Bottled water brands ranked by hardness

Hardness here is calculated from each brand's published calcium and magnesium values using the formula 2.5 × Ca + 4.1 × Mg.

Brand	Country	Ca (mg/L)	Mg (mg/L)	Hardness	Class
Gerolsteiner	Germany	348	108	1314	Very hard
S.Pellegrino	Italy	164	49.5	613	Very hard
Perrier	France	147	3.4	381	Very hard
Borjomi	Georgia	60	50	356	Very hard
evian	France	80	26	307	Very hard
Topo Chico	Mexico	47	27	229	Very hard
Mountain Valley Spring Water	USA	67	7.3	197	Very hard
Acqua Panna	Italy	33	6.5	109	Moderately hard
Deer Park	USA	35	5	108	Moderately hard
FIJI Water	Fiji	18	14	103	Moderately hard
Zephyrhills	USA	30	4	91	Moderately hard
Saratoga Spring Water	USA	17	4	59	Soft
Arrowhead	USA	17	3	55	Soft
Waiākea	USA	10.5	2.4	36	Soft
Poland Spring	USA	7	1	22	Soft
Icelandic Glacial	Iceland	5.6	1.4	20	Soft
Dasani	USA	2	2	13	Soft
VOSS	Norway	2.7	0.61	9	Soft
Essentia	USA	1	1	7	Soft
smartwater	USA	1	1	7	Soft
Core Hydration	USA	1	1	7	Soft
LIFEWTR	USA	1	1	7	Soft
Aquafina	USA	0	0	0	Soft