Water hardness in Tukwila
1.5 gpg soft
Tap water in Tukwila is soft: 1.5 gpg (26 mg/L · 1.4 °dH · 2.6 °fH).
Source: City of Tukwila Drinking Water Annual Report for 2025 (2025) · data checked 2026-11-02
Tukwila's water department is supplied through the Seattle Cedar supply. The city's annual report for 2025 gives 25.7 mg/L, which is soft. The report gives a single value and no range. Scale is minimal, and a softener is not needed.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 1.5 gpg |
|---|---|
| Utility | Tukwila Water Department (Seattle Cedar supply) |
How Tukwila compares
- Tap water in Tukwila is 83 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 1298 of 1372 in the United States (1 = hardest); 5 % of these cities have softer water.
- In Washington it is number 21 of 27 cities; the regional median is 2.8 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 Tukwila
| 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 Tukwila water hard or soft?
It is soft: 26 mg/L as CaCO₃ (1.5 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 Tukwila 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 Tukwila water?
1.5 gpg, equal to 1.4 °dH, 2.6 °fH or 26 mg/L calcium carbonate.
What dishwasher salt setting should I use in Tukwila?
For 26 mg/L (1.4 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in Tukwila?
No. With soft water a softener adds nothing.
Source
Source: City of Tukwila Drinking Water Annual Report for 2025 (2025). Method: figure published by the water supplier. City of Tukwila Drinking Water Annual Report for 2025 · Outdated figure? Tell us