Testing microplastics in tap water vs bottled water can be done through several scientific methods. Here's a breakdown of how it's tested, what differences typically emerge, and how you might approach such a test practically (if you're considering doing it or commissioning one).
How Microplastics Are Tested in Water
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Sample Collection
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Collect at least 1 liter of each sample (tap and bottled).
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Use glass or stainless steel containers to avoid plastic contamination.
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Filtration
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Water is filtered through very fine filter paper (usually 0.45 ?m or smaller).
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This captures particles, including microplastics.
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Digestion (Optional)
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Organic material in the sample is chemically digested (e.g., with hydrogen peroxide) to isolate plastic particles.
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Microscopy + Spectroscopy
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Use microscopes (light or fluorescence) to visually identify particles.
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Use FTIR (Fourier-transform infrared spectroscopy) or Raman spectroscopy to confirm if particles are plastic and identify the type (e.g., PET, PE, PP).
Typical Findings
| Water Type |
Avg. Microplastic Particles per Liter (approx.) |
Common Polymers Found |
| Tap Water |
0–20 particles/L (depending on country/region) |
PE, PP, nylon |
| Bottled Water |
50–300+ particles/L (much higher on average) |
PET, PP (from bottle/cap) |
A 2018 study by Orb Media tested 259 bottles and found 93% contained microplastics.
Want to Test It Yourself?
You can:
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Send samples to a lab that does environmental or food-grade microplastic testing. Labs charge from $300–$1,000 per sample.
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DIY with microscopes and filter paper – possible but less accurate and only visual (no polymer ID).
Example certified labs:
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Eurofins (Global)
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ALS Environmental
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SGS
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Microplastic Lab (Europe-based specialized service)
Summary
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Bottled water typically contains more microplastics than tap water, largely from packaging.
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Testing requires careful filtration, identification, and polymer analysis.
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For accurate results, use lab-based FTIR/Raman testing.
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Microplastics
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Size range: 1 ?m (micrometer) to 5 mm (millimeters)
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Anything smaller than 1 ?m is often called nanoplastics
Microplastic Size Categories (UNEP, WHO definitions)
| Category |
Size Range |
Examples / Notes |
| Large microplastics |
1 mm – 5 mm |
Visible plastic fragments, pellets, fibers |
| Small microplastics |
1 ?m – 1 mm |
Invisible to naked eye, common in water |
| Nanoplastics |
1 ?m (1000 nanometers) |
Very difficult to detect; potential for cell entry |
Typical Sizes Found in Water Studies
| Source |
Typical Size Range Observed |
| Tap water |
10 ?m – 500 ?m |
| Bottled water |
6.5 ?m – 100 ?m (some up to 1000 ?m) |
| Ocean samples |
1 ?m – several mm |
For context:
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Human hair is ~70 ?m in diameter
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White blood cell is ~10–12 ?m
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