Water hardness by state
How hard is the water in Washington?
Tap water in Washington averages 11.1 grains per gallon (190 ppm calcium carbonate). That number determines how fast limescale coats your water heater, shower glass and appliances.
Sur la base de 76 mesures issues de 42 points de surveillance, 2018-08 → 2023-09.
Dureté de l’eau par comté — Washington
Médianes des mesures relevées dans chaque comté. La dureté varie beaucoup plus à l’intérieur d’un État qu’entre États voisins : c’est de là que vient réellement votre valeur.
| Comté | gpg | mg/L | Fourchette (mg/L) | Classification |
|---|---|---|---|---|
| Grant County | 11.9 | 203 | 135–286 | Moderately hard water |
| Kitsap County | 13.6 | 232 | 106–1770 | Moderately hard water |
| Whatcom County | 6.4 | 109 | 57–119 | Soft water |
La fourchette correspond aux 10e-90e centiles des mesures locales. Les comtés comptant moins de cinq mesures sont omis plutôt qu’estimés.
What 11.1 gpg means in Washington
At this level limescale builds up slowly but steadily. White traces appear on faucets and shower glass within months, and the water heater loses a little efficiency every year. Light protection already pays off.
What it does to your home
Water heater: even a thin layer of scale insulates the heating element and drives energy use up.
Appliances: dishwashers, washing machines and coffee makers scale up and fail years early.
Fixtures and skin: white spots on faucets and glass, dry skin and dull hair after every shower.
Comment cette valeur a été obtenue
Median of the site-level medians at 42 groundwater monitoring sites (wells and springs — the sources most US public systems draw from) in the USGS National Water Information System (76 individual measurements, 2018-08 → 2023-09). Each site is collapsed to one value first so that a heavily sampled location cannot skew the state figure; the range shown is the 10th-90th percentile across sites. This describes the raw water resource, not a specific municipal tap after treatment.
Water Quality Portal — USGS National Water Information System (NWIS), characteristic "Hardness, Ca, Mg"Statewide average — hardness varies by utility and season. Always verify with your local water quality report.
Frequently asked questions — Washington
Is 11.1 gpg considered hard water?
On the US scale, 0–3.5 gpg is soft, 3.5–7 gpg moderately hard, 7–10.5 gpg hard and above 10.5 gpg very hard. At 11.1 gpg (190 ppm), water in Washington is classified as Moderately hard water.
Does Washington have a limescale problem?
Water in Washington averages 11.1 gpg — Moderately hard water. The harder the water, the faster calcium carbonate deposits build up in water heaters, appliances and pipes. Below 3.5 gpg the risk is minimal; above 7 gpg scale becomes a running cost.
How do I find the exact water hardness at my address in Washington?
Check your utility's annual water quality report (Consumer Confidence Report) or your water bill, or use our free interactive hardness map. Hardness can vary widely between neighboring utilities in Washington.
Do I need a salt-based water softener at 11.1 gpg?
Not necessarily. Salt softeners add sodium to your water and need constant refills. LIMPEO treats limescale with an electromagnetic field — no salt, no chemicals, no maintenance — and keeps healthy minerals in your drinking water.