Glass vs Plastic Bottled Water: What the Studies Found

The studies we could find don’t show glass bottles to be free of microplastic particles. Two 2018 papers found particles in bottled water from every packaging type they tested, glass included, and both point at caps and the bottling process as likely sources. The better case for glass is recyclability and not being plastic, not an absence of particles.

What did the studies measure?

The biggest one is Mason, Welch and Neratko’s 2018 paper in Frontiers in Chemistry. They tested 259 bottles from 11 brands bought in nine countries. Of those, 93% showed some sign of microplastic contamination. After correcting for lab background, they found an average of 10.4 particles larger than 100 micrometres per litre, and 325 per litre once smaller particles were counted. The most common polymer among the larger particles was polypropylene, at 54%, which matches a common plastic used for bottle caps.

Only one of their lots came in glass. Every bottle, glass or not, had a plastic cap.

What did they find about glass?

In Mason’s data, the one glass-bottled lot (Gerolsteiner) averaged 204 particles per litre, against 1,410 for the same brand in plastic. Lower, but not zero, and the authors read it as a sign that some contamination comes from the water source and a larger share from the packaging.

A second 2018 paper, by Schymanski and colleagues in Water Research, used Raman spectroscopy, which can see smaller particles. They tested 22 returnable and single-use plastic bottles, 3 beverage cartons and 9 glass bottles from German shops. Particles turned up in every type. Returnable plastic averaged 118 particles per litre, glass 50 (range 0 to 253), single-use plastic 14 and cartons 11. Their blank samples averaged 14. Only returnable bottles differed from the blank in a statistically significant way.

So the two studies don’t agree on a winner. In one, glass beat plastic. In the other, glass came out above single-use plastic. Schymanski’s team suggested that caps treated with lubricants may release particles into glass-bottled water, and that the packaging itself can release microparticles.

How much should you read into this?

Not too much. The sample sizes for glass are small: six bottles in one study, nine in the other. The methods differ, and so do the size ranges counted, which is why the averages are so far apart (325 against 14 per litre for single-use plastic). Mason’s team noted that particles under 100 micrometres could not be confirmed as plastic spectroscopically. And Mason says plainly that the human health impact of microplastics is still unknown.

One more detail. Comparing against an earlier tap water study, Mason found bottled water had roughly twice as many particles above 100 micrometres as tap water, 10.4 against 5.45 per litre. The authors’ conclusion was to bottle less water where tap water is safe. We think that is a fair point to put on a page written by a bottled water brand.

So why choose glass?

For reasons other than particle counts. Glass isn’t plastic. It doesn’t depend on oil as a raw material. And it recycles well: the EU’s glass packaging collection-for-recycling rate was 80.2% in 2022, and the industry body FEVE describes glass as infinitely recyclable in a closed bottle-to-bottle loop.

FRØYA is bottled at the source in glass, in two designs: Dorica in 0.25, 0.5 and 0.75 L, and Terra in 0.70 and 1 L. The bottle maker, Société Tunisienne de Verreries (SOTUVER), holds ISO 9001:2015, ISO 50001:2018 and FSSC 22000 certificates, shown on the certificates page. Those certify the manufacturer’s systems. They are not a test of the water or a statement about particles.

Does glass change how water tastes?

FEVE, the European container glass federation, says glass is a tasteless and odourless material with no chemical interaction, so nothing transfers to the contents. That is an industry body talking about its own product, and we haven’t run a taste test of our own, so take it as a claim rather than a finding.

FEVE also notes that glass bottles can be reused up to 50 times before being recycled. This site doesn’t describe a FRØYA refill scheme, so for now the practical route is the recycling bin.

What are the downsides of glass?

It is heavier, so shipping a litre of water in glass takes more fuel than shipping it in plastic. It breaks. And making it takes a lot of heat. FRØYA ships worldwide, so the footprint of a bottle that crosses continents is real whatever it is made of.

We have not published a cap material or a microplastics test of our own, and we won’t imply a result. What we have published is the water analysis. For what is in the water, see how to read a bottled water analysis, and for how the source works, what glacial water is.

What can you do as a buyer?

Return the glass to a recycling bin. FRØYA’s site asks for exactly that.
Choose a size you will finish, so you aren’t pouring water away.
If your tap water is safe and tastes fine, use it for everyday drinking and keep bottled water for when its character is the point.

Frequently asked questions

Is glass or plastic bottled water better?

Glass is recyclable and isn’t plastic, but two 2018 studies found microplastic particles in glass-bottled water too, so it is not particle-free. The studies disagree on whether glass or single-use plastic carries fewer particles.

Does glass bottled water contain microplastics?

It can. Mason et al. found particles in a glass-bottled lot (204 per litre), and Schymanski et al. found an average of 50 per litre in glass-bottled water. Both studies point at caps and bottling as likely sources.

Is bottled water safer than tap water?

Not by the evidence here. In Mason’s study, bottled water had about twice as many particles above 100 micrometres as tap water in an earlier study (10.4 against 5.45 per litre). The authors recommended bottling less water where tap water is safe. Health effects are still unknown.

Can glass water bottles be recycled?

Yes. The EU collected 80.2% of its glass packaging for recycling in 2022, and the industry body FEVE describes glass as infinitely recyclable in a closed bottle-to-bottle loop.

What bottles does FRØYA use?

FRØYA is bottled at the source in glass: Dorica in 0.25, 0.5 and 0.75 L, and Terra in 0.70 and 1 L. The manufacturer, SOTUVER, holds ISO 9001:2015, ISO 50001:2018 and FSSC 22000 certificates.

Sources

Figures for FRØYA come from Eurofins report AR-18-MO-004161-02 (sample taken 20 March 2018, report dated 11 April 2018), which covers one sample. Figures for other brands are taken from the pages linked above and may have changed since. This article is general information about water, not medical advice.

Glass vs Plastic Bottled Water: What the Microplastics Studies Found