Steve Michaelson wrote:

It may be worth a try, as water will still keep moving, but your
fountain (or waterfall) may be going very slow during rainy weather.


And in rainy weather you'd be able to tell, how?

Besides all those droplets hitting the water have got to be ok for all
the things you'd want a fountain/waterfall for anyway, right?

;-)

-Donald
--
But... How do I treat the rain water as it gets into the pond? :-)