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Expert panels/Panel statement
Not enough evidenceVersion 1 · issued 18 Aug 2026 after 72 hours · revisit when the method trial reports · 5 experts · Illustrative

Panel statements: insufficient evidence

Does the 2026 microplastics filter standard protect municipal drinking water?

The panel can’t answer yet. The standard tests particles of 20 µm and larger, but the health questions concern much smaller ones, and there is no validated way to count those in treated water at scale.

What the panel needs to answer
What the standard shows. Filters that meet it remove over 95% of particles of 20 µm and larger. The evidence for this is good.What it doesn’t show. Particles under 1 µm, which can cross the gut wall in animal studies, aren’t measured. Without a method, nobody can say whether filters remove them.What would settle it. An inter-laboratory trial of a counting method for particles under 1 µm in treated water, run in at least three labs. One is planned for 2027.Until then. The panel makes no claim either way. Utilities shouldn’t describe the standard as protecting health from microplastics.
How the panel voted
4 evidence insufficient1 would say yes, with caveats
Evidence used
Filter performance trials, 6 utilities (2025)>95% removal at ≥20 µmSupports, ≥20 µm only
Particle counts below 1 µm (2024)Lab method; not validated on treated waterNot usable yet
Gut uptake in animal models (2023)Uptake below 1 µm onlyContext
Inter-lab method comparison (2025)Counts varied 10× between labsNo agreement
Scope of this statement
Bottled water and household filters.Whether microplastics in water cause harm at current levels.Particles between 1 and 20 µm, which the standard also doesn’t test.
How this statement was made
15 Aug 09:00Question received from the Municipal Water Utilities Network
15 Aug 13:205 of 5 seats filled from 11 eligible experts
16 AugEvidence pack: 4 studies
17 AugThe panel agreed the question can’t be answered with current methods
18 Aug 09:00Vote: 4 insufficient, 1 yes. Statement published
2027Revisit when the inter-lab method trial reports
Panel · 5 expertsEach panellist’s vote and declared interests
HLReviewerWater treatment engineering · chairNone declaredInsufficient
ASReviewerAnalytical chemistryNone declaredInsufficient
OBReviewerToxicologyNone declaredInsufficient
Requested by
Municipal Water Utilities Network · 15 Aug 2026The requester paid for the panel; CitePep chose its members, and the requester saw the statement when it was published.
Cite this statement
CitePep Expert Panel (Lindberg H., chair). The 2026 microplastics filter standard and drinking water. Statement of insufficient evidence, version 1. 18 Aug 2026.
Have new evidence?Goes to the chair. If it changes the answer, a new dated version is issued.