Are Microplastics in UK drinking water: How bad is it ?

The short answer is:

Microplastics are present or potentially present, but current evidence does not show that the levels in UK drinking water pose a significant human-health risk. The bigger issue is that we still don't know enough about long-term exposure, particularly to very small particles.

What are we talking about?

Microplastics are generally plastic particles less than 5 mm across. They can enter water from:

• degradation of plastic products

• wastewater and sewage effluent

• surface runoff

• industrial discharges

• atmospheric deposition

• plastic pipes, storage tanks and other water-system components

The UK Drinking Water Inspectorate (DWI) says microplastics are widespread in surface waters, but groundwater generally has lower exposure because it is better protected from particulate contamination.

How bad is it in UK drinking water?

There is an important UK data gap.

The DWI's recent advisory work states that it does not currently hold sampling data for microplastics in public or private drinking-water supplies in England and Wales. Water companies are also not currently required to routinely risk-assess microplastics as a drinking-water parameter.

That means we should be cautious about claims such as "X microplastic particles are in every litre of UK tap water." There isn't currently a sufficiently standardised UK monitoring programme to support a reliable national figure.

However, UK research indicates that conventional drinking-water treatment processes such as clarification and filtration can remove a substantial proportion of microplastic particles, reducing the potential exposure.

What about health?

This is where the science becomes more uncertain.

The WHO's assessment found insufficient evidence to establish a human-health hazard from microplastics in drinking water. Its assessment found that the potential risk from the particles themselves, associated chemicals and microorganisms was low based on the available exposure information.

The important caveat is that "low demonstrated risk" isn't the same as "proven harmless."

There are still unanswered questions concerning:

• nanoparticles and extremely small microplastics

• long-term, lifelong exposure

• particles that may cross biological barriers

• additives contained in plastics

• chemicals that can attach to plastic particles

• interactions between microplastics and microorganisms

The DWI specifically identifies gaps in understanding public-health risks and notes that there isn't yet an agreed analytical methodology for monitoring microplastics.

So how concerned should you be?

Microplastics exist in the water environment Established

Some can reach drinking-water supplies Yes

UK tap-water exposure is currently demonstrated to cause significant health effects Not established

There are uncertainties about long-term exposure Yes

Should people stop drinking UK tap water because of microplastics? Current evidence does not support that conclusion

In fact, WHO has said that concerns about microplastics should not divert resources from controlling microbial contamination, which remains a much more significant established drinking-water health risk.