Many of us will still remember the days when we used to be able to purchase milk in glass bottles. In fact, that sound of the milk cart powering up the street and the clinking of bottles is synonymous with bygone decades. However, times have changed and plastic is now the preferred way to store milk. Despite this, glass milk bottles are experiencing something of a surge in popularity again. There are many reasons for this, from environmental concerns to nostalgia. Which is better? And which is less damaging to the environment? Let’s take a look at the advantages and disadvantages of glass milk bottles.

Something of a resurgence

Fortunately, in 2015, Müller, a competing dairy company, decided to invest and with that came growth in Milk & More, a modern milk delivery service where consumers can place their orders online. Further, the service also offers other groceries such as butter and eggs. It has now become the largest milk delivery service in the UK.

A similar service exists in the US called ‘Drink Milk in Glass Bottles’. Another example of a service in resurgence that had started to disappear.

Office deliveries have also become a growth area. Due to higher volumes and higher concentrations of offices in any one area services can deliver more profitably. As such, today we can see more office fridges stocked with glass milk bottles.

So whereas most of us still buy our milk in plastic bottles from the supermarket options for glass bottles still do exist. With this in mind, are they better than plastic?

The Advantages of Glass Milk Bottles

Reusable
The biggest advantage of glass milk bottles is that once we’ve consumed their contents they get returned for reuse. Once returned glass milk bottles are washed and refilled and sent back out to consumers full of fresh milk. Whereas there are transport considerations to take into account, avoiding the production of a new plastic bottle for every milk purchase is a win for glass.

Require Less Energy Per Use
When it comes to whether glass or plastic bottles are better we actually have quite a lot to consider. Glass typically takes twice as much energy to produce and therefore during production can actually generate more C02 than plastic when compared by weight.

However, this is just at manufacture, if you average out the additional energy requirements across the lifecycle of a glass milk bottle which gets used again and again the winner is glass over plastic every time.

Glass is Recycled More
The Container Recycling Institute has found that plastic bottles are recycled at a rate of 29%. In comparison to this, glass has a recycling rate of 37%.
Further, as far as plastic goes, there are many vagaries when it comes to recycling5

W. Mack, "Recycling Plastics: The Problems and Potential Solutions," in Disposal of Plastics with Minimum Environmental Impact, ed. H. Mackinney (West Conshohocken, PA: ASTM International, 1973),

Different types of plastic waste can vary in their recycling. Whereas most curbside collections do take plastic milk bottles, what happens once collected can vary considerably due to the capacity and ability for them to be processed once collected.

What’s more, despite many doing their best, a great deal of the single-use plastic we use ends up in nature. Plastic that enters the sea or landfill will take hundreds of years to break down1
Ioakeimidis, C., Fotopoulou, K., Karapanagioti, H. et al. The degradation potential of PET bottles in the marine environment: An ATR-FTIR based approach. Sci Rep 6, 23501

Glass, on the other hand, has more of a conscious element to it. Glass breaks easily when thrown away and is heavier, both of which people are aware of. As such, consumers seem more likely to carefully recycle a glass bottle than a plastic bottle6

Robert Ball, Shirley M. Lawson, Public attitudes towards glass recycling in Scotland, Waste Management & Research, Volume 8, Issue 3, 1990, Pages 177-192, ISSN 0734-242X, https://doi.org/10.1016/0734-242X(90)90062-R

Meanwhile, glass milk bottles not sent back for refill and at the end of their useful life are 100% recyclable and we can recycle them over and over again. What’s more, glass has a quick turnaround when it is recycled. Once consumers recycle it, it can be reused again within 30 days.
Better still, recycling glass produces less CO2 emissions and consumes less energy than new plastic3

Andreas Schmitz, Jacek Kamiński, Bianca Maria Scalet, Antonio Soria, Energy consumption and CO2 emissions of the European glass industry, Energy Policy, Volume 39, Issue 1, 2011,
This is largely down to the polluting resources required to produce new plastic and that plastic recycling requires more complexity and processing and accordingly higher energy use.

Safer
When it comes to storing and consuming milk, glass milk bottles are safer. Plastic milk bottles come with a number of risks including chemical leaching. Environmental and health hazards of chemicals in plastic polymers and products. Lithner, Delilah. University of Gothenburg, Department of Plant and Environmental Sciences
This means that chemicals can leak into the milk and pose health risks.

Glass milk bottles do not come with the same health concerns. We make glass with natural materials such as sand and limestone. What’s more, it is the only packaging that the FDA classes as fully safe.
Due to its natural composition, glass is chemically inert. This means that it does not consist of reactive chemicals.

Easier to Use
Let’s face it, consumers love simplicity. Plastic milk bottles can leak from the lid when squeezed. We’ve probably all suffered a leaky plastic bottle from time to time.
Whereas a glass bottle retains the same shape and won’t leak when crushed at the bottom of a supermarket bag under heavier items. They’re also more robust and sturdy to hold, of course, you do need to keep them upright.

The disadvantages of Glass Milk Bottles

Glass Bottles Are Fragile
We all know just how flexible plastic bottles are. While glass is undoubtedly strong and has the ability to safely store content, it is also fragile. Any kind of impact can cause the glass to break and this instantly means that it is useless. What’s more, it means that the contents will also go to waste

Glass is also susceptible to sharp changes in temperature. Therefore, a glass milk bottle left on a doorstep can shatter once it is met with warm temperatures.

Heavier
When we compared to the thin plastic milk bottles we have become accustomed to, there is no doubt glass is heavier. As a result, its weight adds to the cost of transportation. Also, it means that consumers will have to pay the price as well as the environment due to the emissions from transporting the bottles.

In this respect, alternative containers such as cardboard or even plastic are a more favourable option. In some instances, manufacturers have attempted to use thinner glass. However, this brings with it a range of other issues.

Glass Can Be Unsafe
A simple accident can cause the glass to shatter and break. This makes it more dangerous than plastic. With shattered glass comes the risk of cuts and what’s more, the broken pieces can also find their way into other bottles if damaged during the manufacturing process.
At any time during the entire process, from manufacturing bottles to filling them to transporting them and even handling by consumers, the glass can pose a safety risk.

Diminishing Freshness
Of course, having a milk delivery will ensure that the milk is as fresh as possible. However, traditional glass milk bottles come with foil tops. Exposure to air can reduce the shelf life of milk once a seal gets broken. Plastic bottles can come with lids that we can re-seal. This ensures the milk can remain as fresh as possible.

It is possible to put lids on glass bottles. However, this would require the use of other materials and that can have a cost implication as well as an implication on the environment if the lid is made of plastic.

Further, the wholly transparent nature of most glass milk bottles can result in the degradation of milk when exposed to light. The slightly translucent plastic alternatives offer a slight advantage here. Of course, it’s not too much a problem as most of us safely store our milk in the dark of the refrigerator.