Water hardness in Shoreline
1.4 gpg soft
Tap water in Shoreline is soft: 1.4 gpg (25 mg/L · 1.4 °dH · 2.5 °fH).
Source: Seattle Public Utilities, Quarterly Surface Water Analysis (Q1 and Q2 2026) (2026) · data checked 2026-10-23
Range across supply zones: 23–26 mg/L.
West Shoreline is served directly by Seattle Public Utilities, with the east side served through the North City Water District, and the supply is the Cedar and Tolt river watersheds in the Cascades. Mountain rain and snowmelt carry few minerals, giving soft water at 24.7 mg/L CaCO₃ (23.3–26.2 mg/L). Scale is rare.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 1.4 gpg |
|---|---|
| Utility | Seattle Public Utilities (direct service west Shoreline; wholesale to North City Water District, east Shoreline) |
How Shoreline compares
- Tap water in Shoreline is 84 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 1305 of 1372 in the United States (1 = hardest); 5 % of these cities have softer water.
- In Washington it is number 22 of 27 cities; the regional median is 2.8 gpg.
- Nearest city with clearly harder water: Renton, 32 km away (4 gpg).
Ranking of the hardest and softest water in the United States →
What it means at home
- Little or no limescale in kettles, water heaters or washing machines.
- Soap lathers easily; water does not dry skin or hair.
- Dishwasher: salt setting at minimum or off.
- No softener needed; a jug filter only changes taste.
How much salt will you use for softening?
No. Water this soft does not need softening.
Descale a coffee machine or kettle about every 6 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Shoreline
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 1 °dH |
| AEG / Electrolux | 1 |
| Beko | 1st |
| Hoover | S0 |
| LG | H0 |
From each brand's manual for the model family named in the source; your model may differ, so check its manual. All brands and how to change the setting →
FAQ
Is Shoreline water hard or soft?
It is soft: 25 mg/L as CaCO₃ (1.4 gpg, 1.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Shoreline safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
How many grains per gallon is Shoreline water?
1.4 gpg, equal to 1.4 °dH, 2.5 °fH or 25 mg/L calcium carbonate.
What dishwasher salt setting should I use in Shoreline?
For 25 mg/L (1.4 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in Shoreline?
No. With soft water a softener adds nothing.
Source
Source: Seattle Public Utilities, Quarterly Surface Water Analysis (Q1 and Q2 2026) (2026). Method: computed from supplier's calcium and magnesium. Seattle Public Utilities, Quarterly Surface Water Analysis (Q1 and Q2 2026) · Outdated figure? Tell us