What’s in the water? Los Angeles’s only natural hot spring, by the numbers
The water at Beverly Zen Hot Springs (formerly Beverly Hot Springs) is a naturally warm, alkaline, sodium-bicarbonate mineral water from an artesian well 2,200 feet deep. A 2019 lab analysis measured a pH of 8.7, total alkalinity of 868 mg/L and very little calcium or magnesium. That chemistry explains why guests describe the water as silky, and it has barely changed since it was first tested in 1931.
Where the water comes from
In 1910, Richard S. Grant was drilling for oil on a wheat field off what is now Oxford Avenue. He struck hot mineral water instead. “Artesian” means the water sits in rock under natural pressure, so it rises up the well bore on its own. It leaves the ground at about 105 °F, and the pools are kept between 96 and 105 °F. The well has historically been reported to yield about 250,000 gallons a day.
The 2019 lab analysis
| Measure | Result | What it means |
|---|---|---|
| pH | 8.7 | Mildly alkaline. Pure water is 7.0; seawater is about 8.1 |
| Total alkalinity | 868 mg/L, all bicarbonate | The defining mineral of the spring |
| Sodium | 543 mg/L | About one-twentieth the sodium of seawater |
| Chloride | 136 mg/L | Lightly salty, far below the ocean |
| Sulfate | 69 mg/L | Low |
| Silicon | 11.2 mg/L | Dissolved silica from the rock |
| Calcium | 1.88 mg/L | Almost none, so the water is very soft |
| Magnesium | 0.87 mg/L | Almost none |
| Potassium | 1.51 mg/L | Trace |
| Boron | 0.56 mg/L | Trace |
| Cadmium, lithium, manganese, zinc | Below reporting limits | Not detected |
Sample collected June 17, 2019, independent laboratory analysis.
Why the water feels silky
Two things stand out in the numbers. First, the water is alkaline, and alkaline water tends to feel slippery: it reacts lightly with the natural oils on your skin, the way a very mild soap does. Second, it is extraordinarily soft. With under 2 mg/L of calcium and under 1 mg/L of magnesium, it has a hardness of roughly 8 mg/L, while anything below 60 counts as soft. There is almost nothing in it to leave a film on skin or hair.
The same water as in 1931
A 1931 analysis by the Smith-Emery Company found sodium bicarbonate as the main mineral, at 82.6 grains per gallon (about 1,410 mg/L), with silica, iron and aluminum oxides, magnesium carbonate and sodium carbonate, sulfate and chloride. If the 2019 alkalinity is reported as calcium carbonate, the usual convention, it works out to about 1,460 mg/L of sodium bicarbonate, within a few percent of the 1931 figure.
From “Wonder Water” to bathwater
In the 1930s the spring was bottled and sold for drinking as “Wonder Water” under the Angelus Club label, at ten cents a gallon, until just after World War II. In 1984 a Korean bathhouse was built over the well, and the water has filled its pools ever since. Today it is for soaking, not drinking: please don’t drink from the pools.
What we don’t claim
Mineral bathing has a long history in Korea, Japan and Europe, and many guests tell us their skin feels softer and their body calmer after a soak. We don’t claim the water treats or cures any condition. If you have a health condition, ask your doctor whether hot soaking is right for you.
Questions about the water
Is Beverly Zen a real natural hot spring?
Yes. The pools are fed from an artesian well, not heated city water. It is the only natural hot spring inside the city of Los Angeles.
How hot is the water?
About 105 °F at the source. The pools run from 96 to 105 °F.
Is the water alkaline?
Yes, with a pH of 8.7 in the 2019 analysis.
Sources: Beverly Hot Springs (Wikipedia: 1910 well, 2,200 ft, 105 °F, 250,000 gallons a day, Wonder Water) · 2019 laboratory report and 1931 Smith-Emery analysis from the spa’s records.