I've noticed that all of the Ranma character got cursed by >falling into one
of the springs. There isn't a single one that got the >curse by being
splashed. Even Herb and associates have to dunk animals >into the desired
spring for the curse to take effect. I suspect that the >cursed water looses
it's effect when removed from the spring.

John Walter Biles sort of followed this idea in "Putting >your heart in the
right place" except that the water was non-permanent >(one-shot actually)...
not powerless.

What are your thoughts on the matter? 

	When Mousse returned to Japan after walking into the Duck spring, he 
brought it's water with him and turned quite a few things into ducks.  It was 
never shown if they kept changing.