pH

Acidity vs. alkalinity, from sour to slippery.

What it is

pH measures how acidic or alkaline water is on a 0-14 scale, where 7 is neutral. Below 7 is acidic, above 7 is alkaline.

In hot springs

Most natural hot springs sit between 6.5 and 9. Alkaline springs (pH 8-10) feel smooth and slippery on the skin; acidic springs (below ~6) can feel astringent. Extremes in either direction can irritate skin and eyes.

Cited benefits and context

The U.S. EPA sets a secondary drinking-water standard of 6.5-8.5 for pH, a range that avoids both corrosive acidity and scale-forming alkalinity (EPA National Secondary Drinking Water Regulations). That standard governs ingestion and plumbing, not soaking.

There is no strong clinical evidence that a specific soaking pH confers a health benefit. Mild alkalinity is generally well tolerated, which is why mildly alkaline mineral springs have a long tradition of recreational and balneological use. The therapeutic effects attributed to alkaline springs in balneology reviews come from the overall mineral-water bathing regimen, not from pH alone (overview of balneotherapy systematic reviews, PMC7383020).

Cautions

Avoid soaking in strongly acidic water (pH below ~5), which can indicate mineral oxidation or contamination and can irritate skin. Rinse off after soaking.

Springs ranked by highest ph (most alkaline)

178 springs with verified ph data · showing top 50 · source: USGS Water Quality Portal

  1. 1

    Dagger Creek Hot Spring

    id · 102°F · primitive

    9.9 pH

  2. 2

    Burgdorf Hot Springs

    id · 102°F · primitive

    9.7 pH

  3. 3

    Trail Creek Hot Spring

    id · 102°F · primitive

    9.7 pH

  4. 4

    Running Warm Springs

    id · 85°F · primitive

    9.7 pH

  5. 5

    Billy Hot Spring

    id · 102°F · primitive

    9.7 pH

  6. 6

    Sacajawea Hot Springs

    id · 108°F · primitive

    9.6 pH

  7. 7

    Ninemeyer Hot Springs

    id · 102°F · primitive

    9.6 pH

  8. 8

    Dutch Frank Hot Spring

    id · 102°F · primitive

    9.6 pH

  9. 9

    Loftus Hot Spring

    id · 102°F · primitive

    9.6 pH

  10. 10

    Holdover Hot Spring

    id · 102°F · primitive

    9.6 pH

  11. 11

    Pistol Creek Hot Springs

    id · 102°F · primitive

    9.6 pH

  12. 12

    Preis Hot Spring

    id · 102°F · primitive

    9.6 pH

  13. 13

    Easley Hot Springs

    id · 102°F · primitive

    9.6 pH

  14. 14

    Queens River Hot Spring

    id · 102°F · primitive

    9.6 pH

  15. 15

    Leggit Creek Hot Spring

    id · 102°F · primitive

    9.6 pH

  16. 16

    Cape Horn Warm Springs

    id · 85°F · primitive

    9.6 pH

  17. 17

    Ninemeier Hot Springs

    id · 105°F · primitive

    9.6 pH

  18. 18

    Twin Springs

    id · 102°F · primitive

    9.5 pH

  19. 19

    Sheep Creek Bridge Hot Spring

    id · 102°F · primitive

    9.5 pH

  20. 20

    Bridge Hot Springs

    id · 102°F · primitive

    9.5 pH

  21. 21

    Smith Cabin Hot Spring

    id · 102°F · primitive

    9.5 pH

  22. 22

    Willow Creek Hot Spring

    id · 102°F · primitive

    9.5 pH

  23. 23

    Gold Fork Hot Spring

    id · 102°F · primitive

    9.5 pH

  24. 24

    Bear Valley Hot Spring

    id · 102°F · primitive

    9.5 pH

  25. 25

    Jerry Johnson Hot Springs

    id · 102°F · primitive

    9.5 pH

  26. 26

    Colgate Warm Springs

    id · 85°F · primitive

    9.5 pH

  27. 27

    Bull Creek Hot Springs

    id · 102°F · primitive

    9.5 pH

  28. 28

    Indian Hot Springs

    id · 102°F · developed

    9.4 pH

  29. 29

    Skillern Hot Springs

    id · 102°F · primitive

    9.4 pH

  30. 30

    Barth Hot Springs

    mt · 102°F · primitive

    9.4 pH

  31. 31

    Hot Sulphur (Miracle Hot) Springs

    id · 102°F · primitive

    9.4 pH

  32. 32

    Granite Creek Hot Spring

    id · 102°F · primitive

    9.4 pH

  33. 33

    Red River Hot Springs

    id · 102°F · primitive

    9.4 pH

  34. 34

    South Fork Plunge

    id · 102°F · primitive

    9.4 pH

  35. 35

    Rosalys Warm Spring

    id · 85°F · primitive

    9.4 pH

  36. 36

    Robinson Bar Hot Springs

    id · 102°F · primitive

    9.4 pH

  37. 37

    Brown Creek Hot Spring

    id · 102°F · primitive

    9.4 pH

  38. 38

    Riggins Hot Springs

    id · 102°F · primitive

    9.4 pH

  39. 39

    Mormon Ranch Warm Spring

    id · 85°F · primitive

    9.4 pH

  40. 40

    Hot Springs (Hailey)

    id · 105°F · primitive

    9.4 pH

  41. 41

    Sunflower Hot Springs

    id · 130°F · primitive

    9.3 pH

  42. 42

    Bonneville Hot Springs

    id · 102°F · primitive

    9.3 pH

  43. 43

    Wardrop Hot Spring

    id · 102°F · primitive

    9.3 pH

  44. 44

    Upper Loon Creek Hot Springs

    id · 102°F · primitive

    9.3 pH

  45. 45

    Teapot Hot Spring

    id · 102°F · primitive

    9.3 pH

  46. 46

    Thomas Creek Ranch Hot Spring

    id · 102°F · primitive

    9.3 pH

  47. 47

    Shower Bath Springs

    id · 102°F · primitive

    9.3 pH

  48. 48

    Belvidere Hot Spring

    id · 102°F · primitive

    9.3 pH

  49. 49

    Goat Hot Springs

    id · 102°F · primitive

    9.3 pH

  50. 50

    Salmon Falls Hot Spring

    id · 102°F · primitive

    9.2 pH

Sources

← All minerals