大沢山温泉
O-sawayama OnsenSampled at wellhead
塩
Chloride
+ Bicarbonate
Classification
Sodium Chloride-Bicarbonate spring
A cold-mineral spring (under 25 °C) drawn from the hills of Uonuma, Niigata, reheated for bathing. A sodium-led chloride water layered with a softening bicarbonate sub-type — weakly alkaline, with a faint salt tang on the lips and a trace of rotten-egg note from H₂S. The metasilicic acid content (82.7 mg/kg) leaves the skin noticeably smooth.
Source temperature
26.5°C
Cold mineral
Tonicity
1.02g/kg
Hypotonic
Flow rate
90L/min
Typical
- Color
- colorless and transparent
- Taste
- slightly salty
- Odor
- faint hydrogen sulfide
Highlights
- Cold mineral
- High silica
Analyzed Jul 8, 2025·一般社団法人 新潟県環境分析センター