There's a post I saw on reddit that points to the dimple on the side of a milk jug, and makes fun of all the people who don't know what that's for. In the comments are thousands of people giving dozens of different explanations, and all of them are wrong.
It is not there to indicate that the milk has spoiled by popping out due to gasses produced by spoiled milk. If there was enough gas to pop out the dimple, the whole jug would look like a balloon.
It is not there to provide structural integrity, like lateral support to prevent the bottles from crushing. The contents are under pressure, so if there was enough force on the jug from any direction, then the cap would pop off regardless of the shape in the sidewall.
The actual answer is that the dimple is added to ensure that all of the jugs contain the same volume of milk. Plastic jugs are blown into molds, and minor manufacturing variations over time would create jugs that hold different amounts of milk. Larger jugs would hold more than a gallon. They could just fill by volume, but consumers are wary of purchasing a bottle if it appears to be less full than the others. So they add the dimple to make it so that the level of milk is all the way at the top with minimal air between the milk and the cap.
You can verify this yourself by finding different jugs from the same supplier with dimples of different depths, or even no dimple at all. None of those other explanations would explain dimples of different sizes or jugs without dimples.
TLDR everybody is wrong. The milk jug dimples are added to ensure the jug contains the correct volume of milk.
Wait.....the rest of the world doesn't have hard jug gallons? What do they use instead?
Bags
That.....looks so messy! I know there's no crying over spilled milk, but have you SEEN the price of dairy??? Gotta work a second job just to afford breakfast!
It's not messy, unless you make it messy.
You put em bags into a hard pitcher thing you have at home, and cut the corner. So I guess it's a bit less waste
That guy REALLY should have put an explanation there. Afaik there's one province in Canada that still uses bags. Historically (30 years ago) many countries have used bags. Today most use either tetrapak, smaller bottle style plastic (0.25, 0.5, 1.0 litres) or actual bottles.
Isn't that an Atlantic Canada thing? I know Quebec has them, and I'm pretty sure we weren't the only ones in Canada with bagged milk.
How much does milk cost where you live? Maybe it's just because I live close to the source but milk is around $3 a gallon for me. For another data point eggs are around $2 a dozen, often on sale for $1 (current exchange rates are around 1:1 for dollars to euros for those in euroland)
I miss bag milk. :(
So jealous.
1l cartons
In Sweden we use 1 to 1,5L cartons.
Futuristic technologies such as these
What accursed alien unholy wizardry is this burn my eyes burn my eyes
Just to add, in Brazil we usually have 1l cartoons of UHT milk or 1l bags of pasteurized milk.
Pasteurized milk goes bad in 3 days or so, and many people can't run through the entire 1l in that time. UHT milk will last for a good 2 weeks after opened, so I guess that's the kind you buy.
Here in Australia we have:
1L Jug
2L Jug
3L Jug
1L Tetra Packs (Less common, more often for UHT milk)
1L Hard Plastic Bottle (Less common, more often for high priced 'fancy' milk/plant milks)
In the U.S. milk comes in half gallon and gallon measures, which look like your 2L and 3L containers, respectively.
Sometimes you will find milk in waxed paper cartons, but that is not the norm. (It’s very common, however, for dairy products that are often bought by pint and quart — typically half and half, heavy cream, or coffee creamers.) Our fancier non-dairy creamers tend to be in tetrapaks or cartons, with less expensive (or at least distributed in higher volumes) creamers in plastic bottles.
In Canada, they use gallon sized plastic bags
I've lived in various provinces in Canada. West of Ontario I really only see the waxed-paper cartons or the plastic jugs, stores carry both equally. Eastern Canada carries the plastic bags (and everyone has a plastic container at home they place them in after snipping the bag corner) and often the cartons. Bit weird the custom changes across Canada, and coming from the west I was very confused about the bagged milk when I first moved to Ontario.
Maybe someone else can comment on their experiences. I've never seen bagged milk in a store in the prairies (but I only lived in major cities).
They had milk in 1.3 L bags (sold in packs of 3 for 4 L) in Manitoba about 35 or 40 years ago.
Tbh, I haven't seen bagged milk for quite a while where I live in Canada. It's typically cartons for 2L or less (though sometimes mini plastic jugs too) and plastic jugs as in OP for 4L.
Still very much a thing in Eastern Canada.
Interesting how it varies across the country.
Well, a bag holding 3 x 1.3L bags.
When I grew up here in Sweden, milk came in these containers:
https://en.wikipedia.org/wiki/Tetra_Brik
The design of milk packaging is quite interesting;
https://kommerduihag.se/kommer-du-ihag-hur-mjolkpaket-sag-ut-forr/
15 years or so ago the Brik was changed to this:
https://www.arla.se/artiklar/var-vanligaste-forpackning/
It was apparently done for two reasons:
A smaller version of the tetrahedron style package is still in use for coffee milk.
One liter (0.26 gl) bottles or boxes.
Square space efficient packaging that you can finish within spoiling time, allowing for fresher products without additives. Easier to pour, packaging easily collapses for easier disposal. Fully printable and recyclable. A superior packaging in every single way.
Bags I think.