Can a 5 gallon carboy be used for secondary,Or do I need to use glass?
As long as its made for beer. Don’t use cheap water bottles.
If you are asking if the water bottle from Walmart and such can be used, it might be OK to use. They may be a different plastic than the Better Bottle/NB Bubbler and such. Check the recycle codes.
Do some research and decide for yourself.
It’s a cheap water bottle! I don’t think I’ll use it.