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Water Hardness by ZIP code

How hard is your water?

Enter your ZIP to see where your area sits on the scale, and how sure that is. Then make it exact with your own test.

Free · no account · a county estimate first, then your own test makes it exact
Tap a band to see what it means at home
Sample reading

Every reading tells you how sure it is.

This is what we hold for ZIP 90210, set out the way your own result will be. It’s an example, not your water.

  1. The numberIn mg/L as CaCO₃ and in grains per gallon.
  2. Where it comes fromMeasured at a home, told to you, or estimated for the area.
  3. What it rests onThe samples, the places and the years behind it.
  4. What it lets you doWhether it’s enough to size a softener yet.
ZIP 90210Los Angeles County · Sample, not your water
County estimate, not your tap.
151–224mg/L as CaCO₃ · 8.8–13.1 gpg · Range held, no midpoint
On the scaleHard to very hard
Source
Published national data, snapshot c2f28e1c12fe25b95813d39f3ca5b9e1 · 2010-01-01..2026-08-13
Basis
664 samples from 426 sites · 2010–2025
Implication
Needs information: No household measurement. You can explore sizing with the county estimate, which isn’t your tap. A test of your own water makes the sizing yours.

From published national water data for ZIP 90210. The water in any one home can differ.

The strongest answer

Test it yourself

Your own result beats any area estimate. Follow your kit’s instructions. Here is what we need from it, so your reading counts as a measurement.

  1. Use water that skips any treatmentCold water from a tap with no filter or softener on it, often the kitchen tap. If every tap is softened, take it before the softener.
  2. Test it the way your kit saysA test strip, a drop-count kit or a digital meter all count. Follow the timing on the pack.
  3. Note the number and its unitExactly as your kit prints it: gpg, mg/L or ppm. We do the converting.
  4. Note where and whenWith the date, the method and where you took it, your result counts as a measurement, not just your statement.
Which did you use?

Already have a number? Get a stronger answer.

Your own reading beats any area estimate
Someone gave you a number?

See where it sits on the scale

Declared · not measured by WaterDecoder or you
Who gave it to you?
Grains per gallon–gpg
Milligrams per liter–mg/L as CaCO₃
Parts per million–ppm as CaCO₃

Type the number to see it on the scale.

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