Water hardness in Cheonan
124 mg/L hard
Tap water in Cheonan is hard: 124 mg/L (7.2 gpg · 6.9 °dH · 12.4 °fH).
Source: K-water / 충청남도 천안시 via data.go.kr (2025) · data checked 2026-10-20
Range across supply zones: 93–156 mg/L.
Cheonan reports a median of 124.0 mg/L CaCO₃ for its treated water in 2025, with plants ranging from 92.5 to 155.5 mg/L. This area belongs to the Geum River basin, where Daecheong Dam supplies water; the utility's own raw-water source is not confirmed here. At this level scale builds up quickly in kettles, heaters and shower heads, so a softener or scale protection is worth considering.
Korean waterworks report hardness (경도) in mg/L CaCO₃; the drinking-water standard is 300 mg/L (1,000 mg/L for some sources).
Water data
| Total hardness | 124 mg/L |
|---|---|
| Utility | Cheonan-si (충청남도 천안시) |
How Cheonan compares
- Tap water in Cheonan is 118 % harder than the median of the 127 cities we track in South Korea (57 mg/L).
- By hardness it ranks 4 of 127 in South Korea (1 = hardest); 98 % of these cities have softer water.
- In Chungcheongnam-do it is number 1 of 5 cities; the regional median is 75 mg/L.
- Nearest city with clearly softer water: Yesan, 31 km away (51 mg/L).
Ranking of the hardest and softest water in South Korea →
What it means at home
- Fast scale on taps, shower screens and kettle; white spots on glassware.
- Water heater: efficiency loss and element failures within years if unprotected.
- Dry skin and dull hair after showering are common.
- Softener recommended; jug or reverse osmosis for drinking.
How much salt will you use for softening?
Recommended, especially with a heater or boiler: scale cuts efficiency and shortens its life.
Descale a coffee machine or kettle about every 2 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Cheonan
| Brand | Setting for this water |
|---|---|
| Bosch | H01 |
| Miele | 7 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| Hoover | S1 |
| LG | H2 |
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 Cheonan water hard or soft?
It is hard: 124 mg/L as CaCO₃ (7.2 gpg, 6.9 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Cheonan safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Korean waterworks report hardness (경도) in mg/L CaCO₃; the drinking-water standard is 300 mg/L (1,000 mg/L for some sources).
How many grains per gallon is Cheonan water?
7.2 gpg, equal to 6.9 °dH, 12.4 °fH or 124 mg/L calcium carbonate.
What dishwasher salt setting should I use in Cheonan?
For 124 mg/L (6.9 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Cheonan?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: K-water / 충청남도 천안시 via data.go.kr (2025). Method: figure published by the water supplier. K-water / 충청남도 천안시 via data.go.kr · Outdated figure? Tell us