Definition of Aquaretic:
An agent that bind to vasopressin receptors in the renal collecting duct, promoting excretion of solute-free water [Saunders2007].
There appear to be different modes of action. In general, synthetic aquaretic agents antagonize the vasopressin V2 receptor in the kidney, preventing reabsorption of water [https://www.sciencedirect.com/topics/veterinary-science-and-veterinary-medicine/aquaretic].
On the other hand, herbal aquaretics act by increasing glomerular filtration rate [https://www.chicagotribune.com/news/ct-xpm-1999-05-21-9905220023-story.html], [https://www.gruenwalder.de/english/products/asparagus-p/aquaresis.html].