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Water Hardness Check

Tool · Water Check

Water Check: your hardness, what to install, and what it costs

There's no official hardness-by-ZIP-code list, so start from your own number: your utility's water report, a test kit or a lab. Add what you notice — grit, chlorine taste, stains, a rotten-egg smell — and Water Check lists the treatment steps in order, sizes a softener the way Penn State Extension does, and shows price ranges.

1 Your water

Where does your water come from?

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Not set yet — slide, or type the number from your report.

Unit on your report
Where do I find my hardness?

City water: look for "hardness" in your utility's annual water quality report (Consumer Confidence Report). Utilities must send it every year by July 1 — find yours on the EPA site. Not every report lists hardness; if yours doesn't, ask the utility for the number in mg/L or gpg.

Well water: nobody tests it for you. A hardness test kit gives a quick number; a state-certified lab can test hardness together with iron, manganese and pH.

We don't look hardness up by ZIP code: we found no official ZIP-level dataset, and one town can have several water sources.

2 What you notice
3 Household (for softener size)

Defaults follow Penn State Extension's worked example (75 gal per person per day, about a week between regenerations). The Water Quality Association uses about 200 gallons a day for a family of four as a starting point. Your water bill gives a truer figure.

Readout

Updates as you change any answer

— gpg

What to look at, in the order water passes through

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    How Water Check works

    1. Convert and classify. mg/L (ppm) ÷ 17.1 = grains per gallon. The class comes from Penn State Extension's table, in the unit you typed.
    2. Hardness verdict. Penn State Extension: below 7 gpg water "will probably not cause major scaling and soap film". Minnesota Department of Health: above 7 gpg or 120 mg/L "you might need a water softener". Water Quality Association: above 30 gpg softeners may leak hardness, so get a lab analysis and the maker's sizing first.
    3. Steps in order. Sediment filter before a softener (Minnesota Department of Health) and ahead of a carbon filter (Nebraska Extension); oxidized iron and manganese filtered out before softening (Penn State Extension). Where the sources we read give no order — carbon versus softener — ask the maker.
    4. Softener size. people × gallons per person per day × gpg = grains per day; × days between regenerations = capacity. Penn State's example: 75 gal × 10 gpg × 4 people = 3,000 grains/day.
    5. Salt. grains per year ÷ 3,350. An NSF/ANSI 44 efficiency-rated softener removes at least that many grains per pound of salt, so the result is the most it should use at its rated setting. At the 4,000 grains per pound the Water Quality Association recommends, it's less.

    What Water Check leaves out

    • Hardness by ZIP code. We found no official ZIP-level dataset. City water: your annual water quality report (EPA lookup). Wells: a test kit or a state-certified lab.
    • Iron allowance. Sources found disagree on how much extra softener capacity iron needs, so the tool does not add an iron allowance. Ask the manufacturer to size for your lab results.
    • Rated vs. real capacity. Capacity is tested at the maker's salt setting, and efficiency ratings apply only at specific settings. Compare capacities at the setting you plan to use.
    • Anything that affects health. Bacteria, nitrate, lead, arsenic and similar results are for a state-certified lab and your state or local health department, not for this tool. Salt-based softeners add sodium; the Minnesota Department of Health says people with a history of high blood pressure should ask a doctor about drinking softened water. This site doesn't give medical advice.

    Softener prices: hardware alone around $500–$1,500 (Penn State Extension); Fixr's installed range is $1,100–$3,000, with "most homeowners spending $2,500 to install a dual-tank ion exchange system for a 3 to 4-bedroom home".

    Sources

    Number or ruleSource
    Hardness classes (gpg and mg/L)Penn State Extension, Water Softening, Table 1 (updated Sep 8, 2025)
    USGS hardness classes (mg/L)USGS Water Science School, Hardness of Water (Aug 24, 2026)
    1 gpg ≈ 17.1 mg/LWater Quality Association, Scale Deposits: soft water is "<1 grain of hardness per gallon (or <17.1 mg/L hardness)" (NSF/ANSI 44 and 330); Penn State rounds to about 17 mg/L
    Below 7 gpg: probably no major scalingPenn State Extension, Water Softening: levels below 7.0 gpg will probably not cause major scaling and soap film; softening is a matter of preference
    Above 7 gpg / 120 mg/L: "you might need a water softener"Minnesota Department of Health, Home Water Softening (last updated Oct 3, 2022): above 7 gpg or 120 mg/L "you might need a water softener"
    Above 30 gpg: hardness leakage may occurWater Quality Association, Getting Smart About Water Softeners (PDF, 2019)
    75 gal/person/day; grains × days methodPenn State Extension, Water Softening — worked example: 75 gallons per person per day × 10 gpg × 4 people = 3,000 grains per day
    About 200 gal/day for a family of four (starting point)Water Quality Association, Getting Smart About Water Softeners (PDF, 2019)
    About a week between regenerationsPenn State Extension, Water Softening — example: 20,000-grain capacity ÷ 3,000 grains/day = about 6–7 day regeneration
    3,350 grains per lb of salt (NSF/ANSI 44 efficiency rating, minimum)PNNL Building America Solution Center, Water Softeners — an NSF/ANSI 44 efficiency-rated softener has a rated salt efficiency of not less than 3,350 grains of hardness per pound of salt
    4,000 grains per lb recommended settingWater Quality Association, Getting Smart About Water Softeners (PDF, 2019)
    Capacity and efficiency are tied to the salt settingWater Conditioning & Purification, Rick Andrew, "Hard facts: NSF/ANSI 44 residential cation exchange water softeners" (Feb 3, 2013) — capacity is tested at the manufacturer's salt setting; efficiency ratings apply only at specific salt settings
    Iron and manganese: softener conditions, greensand 3–10 mg/L, oxidation above 10 mg/L (combined)Penn State Extension, Iron and Manganese in Private Water Systems (updated May 29, 2025)
    Iron 0.3 mg/L, manganese 0.05 mg/L (nuisance levels)U.S. EPA, Secondary Drinking Water Standards: Guidance for Nuisance Chemicals (updated May 26, 2026)
    Softeners and iron: up to 5–10 ppm by the maker's ratingNebraska Extension G1491, Drinking Water Treatment: Water Softening (Ion Exchange) (revised Sept 2014)
    Iron can foul softener resin; sediment filter before a softener; sodiumMinnesota Department of Health, Home Water Softening FAQ — iron exposed to air or chlorine can foul softener resin; filtering first may be needed
    Rotten-egg smell: treatment ranges; hot-water-only smellPenn State Extension, Hydrogen Sulfide (Rotten Egg Odor) in Water Wells (updated Dec 10, 2024)
    Sediment filtersNebraska Extension G1492, Drinking Water Treatment: Sediment Filtration (revised Dec 2013)
    Carbon filters; sediment filter ahead of carbonNebraska Extension G1489, Drinking Water Treatment: Activated Carbon Filtration (revised Nov 2013)
    Private wells: annual tests, certified labs, health departmentU.S. EPA, Protect Your Home's Water (private wells; updated Feb 26, 2026)
    Equipment and installed prices by system typeHomeGuide, How Much Does a Well Water Filtration System Cost? (updated Apr 24, 2026) — equipment and installed cost by system type
    Softener prices, labor, running costFixr, Water Softener Installation Cost (updated Jan 31, 2025)
    Hardware-only softener pricePenn State Extension, Water Softening — hardware only, about $500–$1,500
    Annual water quality report (CCR) by July 1US EPA, CCR Information for Consumers (updated Nov 21, 2025)

    Sources checked 2026-11-01.