Lake Toya Onsen has twelve source wells from which spring waters rise from a depth of 60–150 meters.
The waters include sodium and calcium hydrogen-carbonate springs, sulphate springs, and chloride springs, and are reputed to be effective for treating neuralgia, muscle pain, joint pain, cold extremities, burns, scars, and so on.
In particular, the hydrogen-carbonate springs softens the surface of the skin
and emulsifies and washes away fat and secretions. These waters are known as "springs for beauiful women" or "springs for beautiful skin" due to their ability to make the skin soft and smooth.
Some theories suggest that the effects of the spring waters improved after the eruption of Mt. Usu in 2000.