I'm probably being naïve again
Winter storing your waterlily can be done in a lot of ways, a common one around here is to putting it somewhere that doesn't freeze but is cold, like a garage or something. If it's stored cool it doesn't need light, or so I have read.
I don't have that option though so... yeah, I bought a heavy duty bucket (the ones used to make concreate in) and I will have it indoors, I might have to provide it some light. I think that's the issue, and I will probably have to hardy it off when putting it out again next year (if it lives) as it will be used to warm water.
Well, we'll see how it goes. It's just what... four or five month until I can put it back out.
The funny thing is, I was planning to keep this in an aquarium during the winter. I would have needed a gigantic aquarium because it's big and the roots would cause mayhem.