Testing microplastics in tap water vs bottled water; size

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).

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How Microplastics Are Tested in Water

1. Sample Collection

   • Collect at least 1 liter of each sample (tap and bottled).

   • Use glass or stainless steel containers to avoid plastic contamination.

2. Filtration

   • Water is filtered through very fine filter paper (usually 0.45 µm or smaller).

   • This captures particles, including microplastics.

3. Digestion (Optional)

   • Organic material in the sample is chemically digested (e.g., with hydrogen peroxide) to isolate plastic particles.

4. Microscopy + Spectroscopy

   • Use microscopes (light or fluorescence) to visually identify particles.

   • Use FTIR (Fourier-transform infrared spectroscopy) or Raman spectroscopy to confirm if particles are plastic and identify the type (e.g., PET, PE, PP).

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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.

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Want to Test It Yourself?

You can:

• Send samples to a lab that does environmental or food-grade microplastic testing. Labs charge from $300–$1,000 per sample.

• DIY with microscopes and filter paper – possible but less accurate and only visual (no polymer ID).

Example certified labs:

• Eurofins (Global)

• ALS Environmental

• SGS

• Microplastic Lab (Europe-based specialized service)

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Summary

• Bottled water typically contains more microplastics than tap water, largely from packaging.

• Testing requires careful filtration, identification, and polymer analysis.

• For accurate results, use lab-based FTIR/Raman testing.

 

Microplastics

• Size range: 1 µm (micrometer) to 5 mm (millimeters)

• Anything smaller than 1 µm is often called nanoplastics

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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 µm – 1 mm	Invisible to naked eye, common in water
Nanoplastics	<1 µm (1000 nanometers)	Very difficult to detect; potential for cell entry

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Typical Sizes Found in Water Studies

Source	Typical Size Range Observed
Tap water	10 µm – 500 µm
Bottled water	6.5 µm – 100 µm (some up to 1000 µm)
Ocean samples	1 µm – several mm

For context:

• Human hair is ~70 µm in diameter

• White blood cell is ~10–12 µm