Water hardness in San Carlos
2.7 gpg soft
Tap water in San Carlos is soft: 2.7 gpg (46 mg/L · 2.6 °dH · 4.6 °fH).
Source: Cal Water – Bayshore District water quality report page (San Carlos system 2023 report) (2023) · data checked 2026-11-02
Range across supply zones: 8–86 mg/L.
San Carlos is served by California Water Service's Bayshore District, with SFPUC supply. The 2023 report for the San Carlos system gives a median of 46 mg/L as CaCO₃ and a range of 7.5 to 86 mg/L, so the level moves with the source blend. The water is soft, with little scale in daily use.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 2.7 gpg |
|---|---|
| Utility | California Water Service – Bayshore District, San Carlos system (SFPUC supply) |
How San Carlos compares
- Tap water in San Carlos is 70 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 1233 of 1372 in the United States (1 = hardest); 10 % of these cities have softer water.
- In California it is number 308 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
- 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 San Carlos
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 3 °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 San Carlos water hard or soft?
It is soft: 46 mg/L as CaCO₃ (2.7 gpg, 2.6 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in San Carlos 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 San Carlos water?
2.7 gpg, equal to 2.6 °dH, 4.6 °fH or 46 mg/L calcium carbonate.
What dishwasher salt setting should I use in San Carlos?
For 46 mg/L (2.6 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in San Carlos?
No. With soft water a softener adds nothing.
Source
Source: Cal Water – Bayshore District water quality report page (San Carlos system 2023 report) (2023). Method: figure published by the water supplier. Cal Water – Bayshore District water quality report page (San Carlos system 2023 report) · Outdated figure? Tell us