Rain Gutter - PET Bottle Adapter

I have a plant (venus fly trap) which needs rain water, because it doesn't like chalk and would die if I'd water it with tap water.
So I need lots of rain water, which I store in PET bottles, and to get the rain water into the PET bottles, I designed this "Rain Gutter - PET Bottle Adapter". There is a thread in the flange, so the PET bottle can simply be screwed in.