FilterByZip

Regional water-hardness index 40,000+ U.S. zip areas

01Lookup Estimated by zip code

Hard water wears out fridge filters early. Soft water buys you months.

Enter your zip code and we'll estimate how often to replace your refrigerator's water filter, from regional water-hardness data for your area.

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04Method

How the estimate works

  1. Step 1

    Zip code to county. Your zip code maps to a U.S. county — that's the finest grain public water data reaches.

  2. Step 2

    County to hardness. We look up the typical water hardness for that area, in grains per gallon, from regional water-hardness data.

  3. Step 3

    Hardness to schedule. Harder water clogs a 200–300 gallon filter sooner. We adjust the standard 6-month interval up or down — and for your household size, if you tell us.

Read exactly where the data comes from →