Water hardness in Corte Madera
5 gpg moderately hard
Tap water in Corte Madera is moderately hard: 5 gpg (86 mg/L · 4.8 °dH · 8.6 °fH).
Source: Marin Municipal Water District (Marin Water) 2025 Annual Water Quality Report (2025) · data checked 2026-11-04
Range across supply zones: 47–120 mg/L.
2 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| gpg | mg/L | ||
|---|---|---|---|
| Reservoir water | 3.4 | 59 | soft |
| SCWA water | 6.5 | 112 | moderately hard |
Corte Madera is in the Marin Municipal Water District (Marin Water) service area. The district's 2025 water quality report lists two supplies: reservoir water at 59 mg/L (range 47 to 66) and Sonoma County Water Agency (SCWA) water at 112 mg/L (range 110 to 120). The page shows the median, 85.5 mg/L, with the range 47 to 120 mg/L. The report covers the whole district and does not name Corte Madera, and the town's own mix of the two supplies is not stated, so the tap value at your address can fall anywhere between the two figures. If it matters for a softener or scale decision, ask Marin Water which supply serves your street.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 5 gpg |
|---|---|
| Utility | Marin Municipal Water District (Marin Water) |
How Corte Madera compares
- Tap water in Corte Madera is 45 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 1086 of 1372 in the United States (1 = hardest); 21 % of these cities have softer water.
- In California it is number 263 of 336 cities; the regional median is 9.5 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 Corte Madera
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 5 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| 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 Corte Madera water hard or soft?
It is moderately hard: 86 mg/L as CaCO₃ (5 gpg, 4.8 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Corte Madera 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 Corte Madera water?
5 gpg, equal to 4.8 °dH, 8.6 °fH or 86 mg/L calcium carbonate.
What dishwasher salt setting should I use in Corte Madera?
For 86 mg/L (4.8 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Corte Madera?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: Marin Municipal Water District (Marin Water) 2025 Annual Water Quality Report (2025). Method: figure published by the water supplier. Marin Municipal Water District (Marin Water) 2025 Annual Water Quality Report · Outdated figure? Tell us