Does Mountain Valley Spring Water Have Microplastics? Glass, Caps and the Plastic Formats

Has Mountain Valley Spring Water been tested for microplastics?

Not in anything published that we could find. Mason and colleagues’ 2018 study tested 11 brands, none of them Mountain Valley. A 2017 screening of 19 US brands commissioned by the Story of Stuff Project didn’t include it either. The 2024 PNAS nanoplastics study tested three unnamed US brands; there is no basis for linking its roughly 240,000 particles per liter to Mountain Valley.

We also checked the company’s own site on October 18, 2026: product pages, the “Our Water” page, journal posts and the water quality report. None reports a microplastics or nanoplastics test. Searching the site for “microplastic” returns only a 16 oz aluminum product listing whose visible text doesn’t mention the topic.

So the people searching for Mountain Valley’s “purity levels regarding microplastics” won’t find a number, because the company hasn’t published one. What exists is a materials story and a regulated-contaminant report, covered below.

What does Mountain Valley say about its water and glass?

Mountain Valley describes itself as spring water “bottled right at the source, in the Ouachita Mountains” near Hot Springs, Arkansas, and says it has bottled in glass since 1871. Its 2021 journal post says glass “will not leach inorganic chemicals into our spring water during storage or shipping”. A 2018 post makes the case against BPA and polycarbonate. Both are claims about the bottle wall. Neither mentions the cap, liner or bottling line, and neither is a particle test.

The brand became part of Primo Brands when Primo Water merged with BlueTriton in November 2024, so it now shares an owner with Poland Spring, Deer Park and Pure Life. Its 2025 report uses the same template and carries a BlueTriton Brands copyright.

What does the 2025 water quality report show?

The 2025 Water Analysis Report (retrieved October 18, 2026) names a single source, “Mountain Valley Springs, Garland County, AR”. The listed treatment for still water is a storage silo of filtered source water, microfiltration, ultraviolet and/or ozone disinfection, then bottling. Sparkling adds CO₂. No filter pore size is given.

These results describe representative finished product samples tested against FDA and EPA limits. They are reassuring for what they cover. They don’t cover particles, and no US bottled water standard requires a microplastics test. The sparkling water’s low pH is the expected effect of dissolved carbon dioxide.

Does glass mean Mountain Valley has no microplastics?

No, though it likely means fewer sources. We covered the glass evidence in depth in our Voss review, and the short version applies here. Three direct comparisons found glass-bottled water no cleaner than PET:

• France, 2025. ANSES found 4.5 particles per liter in water from glass bottles and 1.6 in plastic bottles and cartons. Particles matched the paint on the outside of the caps. Cleaning caps with air and a rinse cut contamination in a test from 287 to 87 particles per liter.
• Germany, 2018. Schymanski and colleagues measured a mean of 50 particles per liter in nine glass-bottled mineral waters (range 0–253) against 14 in single-use PET. Only returnable PET differed significantly from the blank, and the authors pointed to cap lubricants for glass.
• Germany, 2018. Oßmann and colleagues, counting down to 1 µm, reported 6,292 ± 10,521 per liter in glass bottles and 2,649 ± 2,857 in single-use PET. The spread is wider than the means.

None of these tested Mountain Valley, and the error bars are huge. The fair reading is that glass is not a guarantee. A single lot of Gerolsteiner in glass averaged 204 particles per liter in the 2018 Mason data, against 1,410 for its plastic lot, which shows glass can also come out ahead. Bottle-to-bottle variation and the closure decide a lot. Our guide to bottle caps and microplastics explains the mechanism.

Use the App

Glass, PET or aluminum: know which one is in your fridge

Scan the bottle you buy. The app records the declared bottle and cap material, notes whether that brand has any published test, and suggests lower-plastic options. It reviews product information; it does not measure particles in your water.

Where could particles in glass-bottled water come from?

A glass bottle takes the largest plastic surface out of the package, but the water still passes through several plastic-containing steps before you drink it. The studies above point to four:

• The closure. ANSES matched particles to the paint on cap exteriors, with tiny scratches it linked to caps rubbing together in storage before use. Schymanski pointed to lubricants used on caps.
• The filling line. Pumps, hoses, gaskets and filters at the plant are often polymer. Oßmann found polyethylene and styrene-butadiene particles in glass-bottled water, polymers that aren’t glass or PET, and concluded that sources beyond the package itself have to be considered.
• Air and handling. Fibers settle from the air in any open process, which is why good studies run blanks alongside samples.
• The source water. Groundwater can carry particles, though deep spring sources are usually assumed to carry few. No study has measured the Mountain Valley spring.

The practical point: glass reduces one route that PET bottles have, contact with the bottle wall for months. It can’t guarantee the others. Bottles that go through a returnable washing system add one more step, since Oßmann linked label pigments in reusable bottles to the cleaning process.

What are Mountain Valley caps made of?

Mountain Valley doesn’t say. Its product pages for the 1 L glass and 500 ml PET bottles show photos and pack sizes, with no closure specification. We found no first-party statement on the cap metal, any interior liner, whether the outside is painted, or what seals the multi-gallon glass bottles.

That gap matters more for Mountain Valley than for a PET brand, because the cap is the main remaining polymer contact in the glass bottle. Many screw caps for glass pair a metal shell with a polymer seal, but we can’t confirm Mountain Valley’s design from its own pages. The company could close the question by publishing its closure materials.

You can look at your own bottle. Unscrew the cap and check the inside: a soft disc or ring is a polymer liner, and a painted or printed outside is the kind of surface ANSES traced particles to. Neither tells you how much is shed, but it tells you where the plastic is. If you want to ask the company, the useful questions are the cap material, the liner polymer, whether the exterior is painted or lacquered, and whether caps are cleaned before capping.

Is Mountain Valley in plastic or aluminum the same product?

The water is the same; the contact surfaces aren’t. The current product family page lists still water in four glass sizes, two aluminum sizes and two PET sizes. Mountain Valley says it added aluminum bottles in 2020 and that aluminum “eliminates the problem of plastic waste”. That is a recycling claim. Drink cans and aluminum bottles have an internal polymer coating, explained in are cans lined with plastic? The 16 oz aluminum listing describes it as resealable, so it has a cap too.

Is sparkling Mountain Valley different from still?

The glass sparkling range uses the same source, with CO₂ added, a pH of 5.2 and calcium of 56 mg/L in the 2025 report. Flavored “Sparkling Essences” come in 1 L and 333 ml glass. We found no study that measured microplastics in Mountain Valley sparkling water, and no strong evidence that carbonation itself changes particle counts in glass. The French study found other carbonated drinks in glass had far higher counts than water, about 100 per liter, which it linked to caps. Our guide to microplastics in sparkling water covers the category evidence.

What the evidence does not establish

• A Mountain Valley particle count. No brand test is public, so there is no figure to compare with other brands.
• That glass-bottled Mountain Valley is microplastic-free. Glass removes one source, not all of them, and the closure is undisclosed.
• That it is worse than PET. The glass studies tested other brands in Europe, with wide variation between bottles.
• That microfiltration removes particles you drink. The pore size isn’t published, and closure particles arrive after filtration.
• A health effect. The FDA says current evidence does not demonstrate that microplastics and nanoplastics detected in foods pose a risk to human health. Research on dose and particle type is ongoing.

A useful test would sample several lots of each format, glass, PET and aluminum, with blanks, polymer identification and a stated size range, and test the closures directly.

How do you get the lowest-plastic Mountain Valley, or skip it?

1. Pick glass, not the PET or aluminum formats, if plastic contact is your reason for buying it. Check the label in the store; the brand name alone won’t tell you.
2. Open it once and pour. Repeated opening is where cap friction builds up. A glass carafe on the table beats reopening one bottle.
3. Keep it cool and out of sun, which matters less for glass than PET but still applies to the cap.
4. For home delivery in 5-gallon glass, check the dispenser too. Many have plastic reservoirs, valves or spouts, and the jug’s closure is a separate part. A ceramic crock with a simple tap keeps more of the path out of plastic.
5. Consider filtered tap water instead. A filter with a certified microplastics claim plus a glass bottle gets you a similar setup for far less. See water filters compared and the best glass water bottles.

For brand-by-brand evidence, see the bottled water brands ranked guide and the bottled water brand database, which lists Mountain Valley as not measured.