It depends on what degree of waterproofing is required, long term outdoor storage? or in a shed, loft or garage that you hope is weathertight, but might not be in extreme or exceptional conditions.

I have large stocks of clothing, footwear, blankets and other similar goods.
These are stored in large plastic crates, which are probably watertight, in a loft or roof space that is also probably weatherproof. As an additional and very cheap defence against water damage, each crate is covered with a piece of tarp cut to cover the top and about halfway down the sides, this being secured with bungee cord.

I keep large stocks not just of true survival supplies but of everday clothing, linens etc.
Although the world might end suddenly, I feel a slow slide into the second great deppresion is more likely.
Remember that in the 1930s foodstuffs, clothes, shoes, blankets etc were readily available in the shops, but many went cold, hungry and unshod for want of money to buy these articles.
It could happen again.