Hello, My dad has a outdoor koi pond that's fairly large- three feet deep not sure how wide or long though- if that information is helpful let me know and I'll find out. It has a filtration system and a little riverbed and waterfall. We recently purchased a dehumidifier for our basement and my dad was thinking of using the water to fill the water that has evaporated off the top of the koi pond every once and awhile (once a day maybe every other day). I read on forums that it's not recommended for indoor fish tanks and ponds due to bacteria growth and possible amounts of copper/ aluminum. However, I was curious if the same goes for outdoor ponds? Any help Would be much appreciated! Thanks! P.S. We live in the Northwest if that helps a bit with the outdoor climate.