Thanks.

Of the six potential uses, I think this one is most relevant:

"Forming nouns indicating a process, action or result. E.g. blockage, slippage, shrinkage"

Yet in this case the extension to "wastage" still feels somehow redundant. For example, I wouldn't say "Household wastage in modern society".

I would use "waste" to refer to the physical result, a bunch of trash or whatever. "Wastage" to me is the act, the production of waste.