Water hardness in Renton
4 gpg moderately hard
Tap water in Renton is moderately hard: 4 gpg (69 mg/L · 3.9 °dH · 6.9 °fH).
Source: City of Renton 2026 Water Quality Report (2025 data) (2026) · data checked 2026-10-19
Range across supply zones: 44–125 mg/L.
3 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| gpg | mg/L | ||
|---|---|---|---|
| Downtown Wells | 2.8 | 48 | soft |
| Maplewood Wellfield | 4 | 69 | moderately hard |
| Springbrook Springs | 7.3 | 125 | hard |
The City of Renton's 2025 data lists three sources. Downtown Wells read 48 mg/L (range 44 to 48), Maplewood reads 69 mg/L and Springbrook Springs reads 125 mg/L, all as hardness in ppm. Springbrook is a small spring source, not a distribution zone. The page shows the median of 69 mg/L (4.0 gpg). Hardness depends on which source feeds your area.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 4 gpg |
|---|---|
| Utility | City of Renton Public Works (Utilities) |
How Renton compares
- Tap water in Renton is 55 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 1151 of 1372 in the United States (1 = hardest); 16 % of these cities have softer water.
- In Washington it is number 11 of 27 cities; the regional median is 2.8 gpg.
- Nearest city with clearly softer water: Bellevue, WA, 14 km away (1.4 gpg).
Ranking of the hardest and softest water in the United States →
What it means at home
- Visible kettle scale every few weeks; vinegar or citric acid is enough.
- Water heater and washing machine: some long-term scale; a scale inhibitor slows it.
- Dishwasher: medium salt setting.
- Softener optional; pays off mainly with a gas boiler or tankless heater.
How much salt will you use for softening?
Optional. A scale inhibitor or a small softener protects the heater; soap savings are modest.
Descale a coffee machine or kettle about every 3 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Renton
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 4 °dH |
| AEG / Electrolux | 2 |
| Beko | 1st |
| Hoover | S1 |
| LG | H1 |
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 Renton water hard or soft?
It is moderately hard: 69 mg/L as CaCO₃ (4 gpg, 3.9 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Renton 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 Renton water?
4 gpg, equal to 3.9 °dH, 6.9 °fH or 69 mg/L calcium carbonate.
What dishwasher salt setting should I use in Renton?
For 69 mg/L (3.9 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Renton?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: City of Renton 2026 Water Quality Report (2025 data) (2026). Method: figure published by the water supplier. City of Renton 2026 Water Quality Report (2025 data) · Outdated figure? Tell us