Microplastics in Tap Water: What a 2026 Review Found

Every one of the eight studies that a 2026 systematic review examined confirmed the same thing: microplastics were present in the tap water they tested.[Oliveri Conti et al., 2026] That review, published in the journal Microplastics, pulled together evidence from Europe, Africa, South America, the Middle East, and Asia, and used it to estimate how much of these particles people actually take in through drinking water.

The numbers are not small, and they fall hardest on the youngest. But the same review is unusually candid about how shaky the underlying measurements are — and that honesty is worth reading carefully before anyone panics or dismisses the finding.

What the review actually did

The study followed PRISMA guidelines and was registered on PROSPERO, the international register for systematic reviews.[Oliveri Conti et al., 2026] The authors searched PubMed, Scopus, Web of Science, and Cochrane, and an initial sweep returned 22,650 records. After removing duplicates and screening for relevance, just eight studies met all the inclusion criteria.[Oliveri Conti et al., 2026]

That collapse — from tens of thousands of records to eight — is not a weakness in the search. It reflects how few studies measure microplastics in tap water with enough rigour and enough samples to be usable. The review deliberately excluded studies with fewer than 30 samples, along with bottled-water and natural-water studies not connected to tap supply.[Oliveri Conti et al., 2026] Collectively, the eight studies analysed 586 samples.[Oliveri Conti et al., 2026]

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How much is in the water

Concentrations differed enormously between studies. The average microplastic concentration ranged from essentially zero in a Hong Kong study to 390 particles per litre in a study from Istanbul.[Oliveri Conti et al., 2026] Overall, the reported values spanned roughly 0.0008 to 74 microplastics per litre across the dataset.[Oliveri Conti et al., 2026]

The particles were not uniform. Fibres and fragments were the most commonly identified shapes, with films, spheres, and pellets appearing less often.[Oliveri Conti et al., 2026] Fibrous shapes dominated, representing 77% to 86% of total microplastics in some studies.[Oliveri Conti et al., 2026] Detected sizes ranged from 2.7 micrometres up to more than 5 millimetres, but most fell between 10 and 500 micrometres. In some studies, particles under 1 millimetre accounted for over 98% of everything found.[Oliveri Conti et al., 2026]

The most frequently reported polymers were polyethylene, polypropylene, polyethylene terephthalate, and polystyrene, with ethylene-vinyl acetate, polyamide, polybutadiene, and polyimide showing up less often.[Oliveri Conti et al., 2026] The review notes these come from many sources, including the breakdown of larger plastics, personal care and cleaning products, industrial wastewater, packaging, and the water distribution system itself.[Oliveri Conti et al., 2026]

Children carry the heaviest estimated exposure

To translate concentrations into exposure, the review calculated Estimated Daily Intake (EDI) — the number of microplastics ingested per kilogram of body weight per day — using standardised water-intake and body-weight figures for different age groups.[Oliveri Conti et al., 2026]

The pattern was consistent: the youngest children were exposed to the most, relative to their size. Estimated intake reached up to 39 microplastics per kilogram of body weight per day in children aged 2–3 years, and 35.1 in infants aged 6–12 months, based on concentrations from the Istanbul study.[Oliveri Conti et al., 2026] The reason is straightforward — young children drink far more water per unit of body weight than adults do.[Oliveri Conti et al., 2026]

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Pregnant women fell between children and other adults, with estimated intake reaching up to 14.96 particles per kilogram of body weight per day.[Oliveri Conti et al., 2026] The review flags growing interest in whether microplastics can cross the placenta as a reason this group warrants closer attention.[Oliveri Conti et al., 2026] At the other extreme, the Hong Kong study produced EDI values of zero across every age group, because it detected no microplastics.[Oliveri Conti et al., 2026]

The important caveat: these numbers are indicative, not definitive

This is where the review earns credibility rather than losing it. The authors repeatedly warn that the EDI figures should be read as a comparative exposure metric, not a toxicological benchmark or a precise measurement.[Oliveri Conti et al., 2026]

The methods ranged from basic stereoscopic microscopy to FTIR and Raman spectroscopy for chemical identification, up to high-performance liquid chromatography coupled with mass spectrometry.[Oliveri Conti et al., 2026] These are not interchangeable. Microscopy-based approaches tend to underestimate the smallest particles, while mass-spectrometry methods target different analytes entirely and produce results that cannot be lined up against particle counts.[Oliveri Conti et al., 2026]

The review also assessed the quality of its eight studies using an adapted Newcastle–Ottawa Scale. None was rated “low risk.” Every study was judged to have “some concerns,” largely due to limited transparency in analytical protocols and the absence of pre-registered plans.[Oliveri Conti et al., 2026] The authors further note that most studies did not report measures to control for environmental cross-contamination during sample handling — a known way to inflate counts.[Oliveri Conti et al., 2026]

A separate limitation cuts the other way. Nanoplastics — fragments smaller than 1 micrometre — were rarely detected, mostly because current tools struggle to identify them reliably.[Oliveri Conti et al., 2026] That gap means the true exposure could be underestimated, since the smallest and potentially most biologically active particles are the hardest to count.[Oliveri Conti et al., 2026]

Tap water is only one exposure route

One point the review makes plainly is easy to lose in a headline. Tap water is just one of many pathways through which people encounter microplastics.[Oliveri Conti et al., 2026] The concentrations it reports should be read as the contribution from tap water alone, not as an estimate of anyone’s total daily exposure.[Oliveri Conti et al., 2026]

The review also notes that microplastics in tap water can reach people indirectly — through food prepared or processed with that water, not only through drinking it.[Oliveri Conti et al., 2026] As for health effects, the authors are measured: microplastics are known to accumulate in the human body, and some studies suggest toxic effects, but the review states research on biological impacts is still at an early stage.[Oliveri Conti et al., 2026]

Can treatment remove them?

The presence of microplastics in already-treated tap water suggests conventional treatment does not fully remove smaller particles.[Oliveri Conti et al., 2026] The review cites work reporting 100% removal efficiency for microplastics larger than 5,000 micrometres via ultrafiltration — but notes that efficiency drops for smaller particles and can be affected by membrane fouling.[Oliveri Conti et al., 2026] Advanced technologies, in other words, could help, but no single treatment is a clean fix across all particle sizes.[Oliveri Conti et al., 2026]

The authors’ central recommendation is not a consumer product — it is standardisation. They call for harmonised protocols for sampling, detection, quantification, and reporting, led by the agencies responsible for water quality, so that studies can finally be compared and microplastics can be folded into existing water-safety frameworks.[Oliveri Conti et al., 2026]

What to take from this

The honest summary is that microplastics are consistently found in tap water, that children and pregnant women carry the highest estimated intake per kilogram of body weight, and that the science measuring all of this is still too inconsistent to tell you exactly how much you are drinking or what it does to you.

For most readers, the practical response is proportion, not alarm. The strongest, most defensible takeaway from this review is the one the authors themselves lead with: we need standardised measurement before we can responsibly quantify risk. Until then, treat “microplastics are present in tap water” as an established observation and “here is precisely how much and how harmful” as an open question the evidence cannot yet answer.