Its about the UV, so it'd be quicker in the desert at noon, but should still work on a blowey UK afternoon, but I bet it would take longer.
I dont know if the plastic bottles they have over there are different to the ones pop comes in the UK, but they only last a few weeks after opening the seal, before it startsreleasing chemical nasties.
Other than that I agree, the guy with the bunker should do well. Ifit ever gets that bad, I think the farm & Housewife might struggle though, like the narrator says, they look like they have stuff going spare. Amused to hear her mention OPSEC, then for a wholesalers lorry to make a delivery right on her doorstep. Doh.