You found a water report that says 110 mg/L, or a range from 172 to 302, and you do not know whether that is a lot. A number with no scale feels like a test you cannot pass. Here is the scale, what each band means in plain terms, and how to use it without turning it into a verdict on your hair.
Why mg/L is used
Water reports often express total hardness as milligrams per litre of calcium carbonate, written mg/L as CaCO3. Calcium and magnesium are the main contributors. The carbonate notation lets reports compare those minerals using one conventional unit.
Hardness is not the same thing as general water quality. The World Health Organization does not set a health-based guideline value for hardness. It may affect taste, scale and how soap performs, but the figure alone does not say whether water is safe or unsafe.
Curious how a routine is built from numbers like these? See how Rizzado works, step by step.
See how Rizzado worksThe four USGS bands
The USGS bands are simple: soft is 0 to 60 mg/L, moderately hard is 61 to 120 mg/L, hard is 121 to 180 mg/L and very hard is above 180 mg/L. A report at 110 mg/L is moderately hard. A published span from 172 to 302 mg/L crosses hard and very hard, so the range should remain visible.
A boundary is not a biological switch. Water at 119 mg/L and 121 mg/L belongs to neighbouring descriptive bands, not opposite hair realities. The number becomes useful when it is paired with the source, period and your own routine context.
Use a range honestly
Some utilities report one average. Others report separate values for groundwater, imported water or treatment plants. If your utility gives a range, do not turn it into a false single number. Check its supply map or ask which source generally serves your address.
If you use the scale to make a routine comparison, label it as a practical observation. The current evidence does not define a specific hardness threshold at which every person with curls needs a particular shampoo or filter.
See the scale at a glance
0-60 mg/LModerately hard
61-120 mg/LHard
121-180 mg/LVery hard
180+ mg/L
How to use your band
Find your band on the scale. Moderately hard and hard water are common, and a band alone does not tell you what to change. Use it as a reason to look at practical signs, such as residue after washing or a routine that feels heavier than it did before. These are observations, not proof of hardness.
If your band is hard or very hard, a sensible next step is one controlled change, such as a single wash with a clarifying or chelating product, followed by a comparison over several wash days. If the result does not repeat, treat it as noise.
CITY DATA
Compare a published local source
These pages keep the utility or public authority source next to the figure. They are a starting point for a question, not proof of what is happening to your hair.
Browse every city with a primary source