I was not able to see but I agree with the above answers.
Its piped from underground, after your experience if you watch them drain the tub you can see that they drown it directly into the river/ creek. They can do this because its naturally occurring water
From at least one of the hot tub locations you can see a large pipe across the river. I don't think there is any reason to question that it's not what they claim. We have been there a few times. We love it!
You can't see where the water comes from but it's a wonderful experience.
I was not able to see where the water came from.
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