Actually, Tesla invented this and highlighted to his close friend Mark Twain.
https://www.thevintagenews.com/2019/01/11/twain-and-tesla/
https://racingnelliebly.com/weirdscience/did-nikola-tesla-cure-mark-twains-constipation/
I had no idea that Nikolai Tesla and Mark Twain we’re friends. If you look at Mari Twain’s life it was actually more interesting and adventuresome than his books.
Interesting. And I can personally attest to the need to “empty the reservoirs” before doing WBV. Fortunately, where we have ours installed is in a walk-in closet off the bathroom.