Microplastics Found In Drinking Water

Microplastics are tiny plastic fragments that are found throughout the environment, including in soil and bodies of water. Microplastics are often defined as being between 0.1 and 5000 µm (micrometers) in length - somewhere between the size of the SARS-CoV-2 virus, and the diameter of a typical drinking straw - although there is no uniform definition. They can vary widely in shape, size, and chemical composition, as illustrated here by these comparable items.

Polyethylene (PE), polybutylene succinate (PBS), and polyvinyl chloride (PVC) are the most common microplastics. They are classified as either primary or secondary microplastics. Primary microplastics are manufactured below 5000 µm (5mm) in size for use mostly as industrial abrasives or in cosmetics. These account for less than 0.1% of total plastic production, as per the European Chemicals Agency (2019) and Plastics Europe (2018).

Secondary microplastics are formed by the breaking up of larger pieces when exposed to UV radiation (from the sun), high temperatures, and weathering in the environment. This was confirmed in independent studies in 2014 by Professor Johnny Gasperi of Université Paris-Est Créteil, and by Professor David Morritt of the School of Biological Sciences at Royal Holloway University of London. This infographic shows the different paths for microplastics to enter the environment and was assembled by the team from China’s Northwest University in the iGEM synthetic biology competition.

Microplastics in water may threaten animal and human health by entering the food chain or transporting concentrated contaminants in aquatic environments. Professor Cinzia Corinaldesi, an environmental scientist at the Polytechnic University of Marche, Italy studied the harmful biological effects of microplastics on corals. These microplastics caused tissue abrasions leading to bacterial infections, impairing mucus production, and could even lead to death. The corals exposed to high concentrations of microplastics incurred tissue damage which was 6.5 times that of corals that were not exposed to microplastics or had ingested low concentrations of microplastic after a period of 14 days.

Other studies cited showed negative impacts at molecular, cellular, and population levels on fish, larger marine creatures, and plankton. Disturbances in genetic functions, reproduction, and feeding were identified.

 

For humans, while there is an ongoing debate, drinking water containing microplastics or eating contaminated seafood may pose health threats. For example, the Woods Hole Oceanographic Institution found that certain microplastics in water such as polychlorinated biphenyls (PCBs) are linked to cancer.

A detailed review of earlier studies authored by Claudia Campanale and others at the Water Research Institute of the Italian National Research Council showed that microplastics under 10 micrometers could enter the fluid around the brain and other organs such as the liver, kidneys, and placenta.

As a relatively new area of research, there is uncertainty regarding the level of harm microplastics pose to human health. The latest research by the World Health Organization (WHO) suggests that many studies may be overestimating the health impacts on humans and that microplastics in water are likely to have a minimal effect when properly filtered out in Water Treatment Plants.

The effects and routes that microplastics could take within the body are not well understood. Further research into potential harmful effects on humans and the environment is critical. As shown in this chart, a 2020 risk assessment report by the European Chemicals Agency forecasts that European emission of microplastics could exceed 1.6 million tonnes per annum if proposed restrictions are not put into place.

Which Water Types Have Microplastics?

There are five main water types that have microplastics.

• Tap water
• Bottled water (drinking water)
• Marine water
• Waste water
• Arctic water

Microplastics in each type have unique issues.

1. Tap Water

Tap Water is sourced from a local authority’s water system and is available in private and public buildings as well as some outdoor locations. It can come from any available source including groundwater aquifers, reservoirs, lakes, rivers, or desalinated seawater. Natural sources tend to be of higher initial quality, but all sources are usually filtered and treated to some degree before entering the system for general usage.

How much microplastic is in tap water? In a review of scientific studies by Professor Albert A. Koelmans of Wageningen University in the Netherlands, tap water samples were found to contain between 0.1 to 100 thousand microplastic particles per thousand liters.

This huge range is hard to generalize about, but the amount of plastic manufactured and used in a local area is likely a key factor in microplastic concentrations. As are potential transportation routes into an area such as rivers. Once microplastics have entered nature, they will inevitably enter the tap water system.

While municipal water treatment systems reduce the amount of microplastics to minimal levels, it is rare that they can entirely eliminate them. Even after being treated, water may pass through areas where microplastics can enter the system before reaching the consumer’s tap.

Potential harms and dangers from drinking tap water with microplastics include toxic effects to the digestive tract, links to serious illness such as cancer, a compromised immune system, or infiltration of the blood-brain barrier resulting in neurological complications. When washing or scrubbing, smaller microplastics in tap water could be absorbed through the skin.

2. Bottled Water (Drinking Water)

The US Food and Drug Administration (FDA) defines bottled drinking water as water “intended for human consumption, sealed in containers with no added ingredients except safe and suitable antimicrobials and fluoride within limits”.

How much microplastic is in bottled water? With thousands of bottled water brands around the world from different sources and with different filtration and manufacturing processes, it is not possible to draw a firm conclusion on the amount of microplastics in the category as a whole. hypotheses that bottled water is unlikely to contain microplastics have been repeatedly shown to be incorrect.

Professor Albert A. Koelmans from Wageningen University found that microplastics in the bottled water they sampled varied widely in concentration from 0.01 to 100 thousand microplastic particles per thousand liters. Even in a limited sample range, this variation may be partly from the bottling processes themselves or the use of plastic caps.

In Canada, Dr. Kieran D Cox of the Department of Biology at the University of Victoria found the concentration of microplastics in bottled water brands they sampled to be 22 times higher than tap water.

While research on microplastics in bottled water remains limited due to the wide array of waters that have to be tested to draw clearer conclusions, thus far the research has shown bottled water tends to have higher concentrations than tap water.

But even this conclusion should be taken with caution as bottled water studies tend to measure for smaller particles than tap water studies. This means that the methodology is almost certain to show higher concentrations in bottled water than tap water which may not be correct if the same size particles are tested for.

Two of the main inputs of microplastics into freshwater are surface run-off (when plastic has accumulated around water bodies) and wastewater effluent (plastic present in used water), as illustrated by the following schematic produced by the World Health Organization (WHO) for their 2019 report, Microplastics in Drinking-Water.

Even deposits in the air can add to contamination in water sources. Bottled water utilizing natural sources can then be contaminated by the microplastics, especially if sufficient filtration is not utilized.

Presuming the studies pointing to the harmful effects of microplastics are correct, the tendency towards higher concentrations of microplastics in bottled water suggests a greater risk of health effects. But it must be reiterated that the methodologies between bottled and tap water studies have not matched, and the range of results have been extremely wide and inconclusive.

Regardless of the ultimate answer research finds, a bottled water brand using a well-protected source (such as iceberg water preserved long before plastics existed) and clean bottling processes are most likely to be among those found to have no microplastic content.

3. Marine Water

The Georgia Department of Natural Resources defines Marine Water as water from the sea or ocean having high salt content. Besides the open ocean, marine water can be found in the bilge water of ships.

How much microplastic is in marine water? A citizen science study known as the Global Microplastics Initiative published a report in the journal Environmental Pollution in 2018 where they showed that 90% of 1393 ocean samples from around the world had microplastics, with an average concentration of 118 particles per liter. 91% were microfibers from plastic elements in fabrics. Their measurements at different locations are shown on the map below.

Open ocean samples consistently had higher average concentrations (179 per liter) than coastal regions (59 per liter). The polar regions had the highest concentrations, with the Arctic averaging 313 particles per liter and the Southern oceans 154.

There was significant variation in the Arctic, with Canada and Alaska at the higher end of the range, while Svalbard samples had just 0 to 6 particles per liter. The Atlantic was still above average at 134 microplastic particles per liter, followed by the Pacific at 70 per liter and the Indian Ocean at 42.

Large plastic debris originating from urban environments regularly enters freshwater systems according to the 2014 studies by Professor Gasperi and Professor Morritt. According to Vivian S. Lin of the Institute of Biogeochemistry in Zurich, Switzerland, microplastics enter the environment directly via waste streams that include personal care products, textiles with synthetic fibers (often detached in washing machines), and cleaning agents. From there they can flow into the ocean environment. Discarded plastic fishing nets such as this one erode into microplastics over time.

Microplastics in water can have negative health effects on wildlife and can contribute to the transport of toxins and contamination of the food chain. According to Dr. Lin, they can enter at the bottom of the food chain when ingested by algae, bacteria, and plankton where they leach toxins that damage development and threaten survival. From there the damage moves up the food chain, including via reduced food intake and reproductive success for crustaceans in the middle of the food web as seen in research by Matthew Cole of the UK’s University of Exeter and colleagues.

Another example comes from Dr. Mark A Browne and colleagues from the School of Marine Science & Engineering, Plymouth University and the National Center for Ecological Analysis & Synthesis, University of California, Santa Barbara who noted that lugworms were found to have greater difficulty creating sediment burrows after microplastic ingestion.

Microplastics in marine water are ingested by humans via seafood. Key concerns to human health, in this case, are enhanced inflammatory response, the toxicity of plastic particles, contamination due to adsorbed chemical pollutants, and a disruption in the digestive system. Though these impacts are yet to be fully substantiated.

4. Waste Water

Wastewater is used water and can have human waste, food scraps, oils, soaps, fertilizers, or industrial chemicals present in it.

How much microplastic is in wastewater? A study by Daniel Sol et al. at the Department of Chemical and Environmental Engineering of the University of Oviedo in Spain found that wastewater treatment plants they tested in the United States had between 83.3 and 147 microplastics particles/L when untreated and 2.6 to 17.2 microplastics particles/L after treatment. In some samples, the microplastics were not detected or were very minimal in both the influent and effluent.

This picture shows a large microplastic particle that made it through the Ruhleben Berlin wastewater treatment plant. The picture is from the Humboldt University Berlin team in the 2019 iGEM synthetic biology competition.

Wastewater effluent is a widely recognized source of microplastic pollution into freshwater bodies and in agricultural soil, but effective water treatment can reduce these harmful effects. A study in the journal Environmental Science: Water Research and Technology by researchers at the University of Surrey in the UK found that a three-phase wastewater treatment plant could remove 88-94% of microplastics.

Wastewater can cause harmful effects once it re-enters freshwater sources and drinking water sources. Even the waste from wastewater treatment needs to be handled carefully as this would be a source of microplastics. It can disturb agricultural land by introducing a source of fibers into the soil, which could theoretically be toxic or ingested by humans.

5. Arctic Water

The Arctic region lies above the Arctic Circle at 66° 34' north latitude. How much microplastic is in arctic water? Peter S. Ross and his team at the Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, performed a survey in the Arctic region finding an average of 186 microplastic particles per liter on visual inspection, though this was reduced to a more accurate 40.5 microplastic particles per liter when they used spectroscopic analysis.

Higher microplastic concentrations were detected towards the eastern Arctic which is influenced by the Atlantic Ocean compared to the western Arctic which is influenced by the Pacific Ocean. Seawater samples of arctic water around Svalbard showed close to zero microplastics and icebergs formed in glaciers long before the invention of plastic should have none.

This chart from a study entitled “Microplastics in sea ice and seawater beneath ice floes from the Arctic Ocean” by Kanhai et al. shows concentrations and types of microplastics found in 25 ice cores taken across the North Pole ice cap. Sample 9 was taken almost precisely at the North Pole.

The Global Microplastics Initiative found an almost 8 times higher level of 313 microscopic particles per liter in the Arctic. The different results underscore the difficulty of measuring such broad regions but confirm that the concentrations are worrying no matter which survey is looked at.

It is most likely that ocean currents have carried plastic waste to the Arctic from afar, though comprehensive research on specific microplastic sources in the Arctic is still limited. One known source is discarded plastic fishing nets which regularly wash up on arctic shores from thousands of kilometers away.

Research in 2015 led by Dr. Amy L. Lusher of the Marine and Freshwater Research Centre in Ireland along with the National Institute of Oceanography and Experimental Geophysics (OGS) in Italy suggests that zooplankton, invertebrates, fish, seabirds, and mammals may feed on microplastics. Their surveys found microplastics in 95% of tested surface water samples and in 93% of sub-surface samples. All of which pass through the ecosystem as illustrated by the food web below, and could lead to dangerous toxicological responses or even death.

The International Union for Conservation of Nature (IUCN) points out the human health concerns of arctic microplastics as 40% of US and 50% of European commercial fishing comes from the Arctic region.

How To Measure Microplastics In Water?

There are two ways to measure microplastics in water: visual and spectroscopic.

Visual examination of plastic debris in water is carried out by filtering microplastic particles of a chosen size range. These solids are then dried and exposed to catalysts that can remove organic matter. The plastic material is then analyzed with the help of a dissecting microscope. Using this method, the size range usually falls between 0.3 micrometers to 5 micrometers and is difficult to conduct for smaller size ranges. An article in the Royal Society of Chemistry journal authored by Paul U. Iyare, Sabeha K. Ouki, and Tom Bond at the Department of Civil and Environmental Engineering of the University of Surrey found that organic material could be mistaken for plastic between 20% to 70% of the time.

The second way is to use special spectroscopic machines that study how light interacts with materials. These methods have a much higher resolution and are used to measure concentrations per kilo or per liter. Once samples of water are collected, the organic (non-plastic) matter is removed, and techniques such as FT-IR, focal plane array imaging, and Raman spectroscopy are used to detect and study microplastics. A more detailed explanation of these methods is outside the scope of this article, but interested readers can find out more about how they work from this excellent Crash Course produced by PBS.

What Are The Studies Proving That There Are Microplastics In Water?

Four of the most important studies proving that there are microplastics in water came from the Woods Hole Oceanographic Institution in 1972, the Universities of Plymouth and Exeter in 2008, the Marine and Freshwater Research Centre in Galway, Ireland in 2015, and a meta-study of other research from Wageningen University in the Netherlands in 2019. The term ‘microplastic’ itself was first used in its current meaning only in 2004 and its use has grown quickly in scientific research papers, as tracked by the European Chemicals Agency in 2018 in this chart, showing the number of review papers released each year that relate to this term in the Scopus research database.

The following are the four most important studies on microplastics in water.

1. Microplastics were first observed in a 1972 study entitled “Polystyrene Spherules in Coastal Waters” by a team led by biologist Dr. Edward J. Carpenter of the Woods Hole Oceanographic Institution (now at San Francisco State University). The team discovered small spherical plastic pieces off the north-eastern coast of the United States. They found that hydrophobic contaminants (particles that do not bind easily with water) may stick to the plastic particles.
2. An important 2008 study titled “Ingested Microscopic Plastic Translocates to the Circulatory System of the Mussel, Mytilus edulis (L.)” was conducted by Mark A. Browne, Awantha Dissanayake, Tamara S. Galloway, David M. Lowe, and Richard C. Thompson in joint research by the School of Biological Sciences at the UK’s University of Plymouth and the University of Exeter in 2008. Researchers discovered plastic particles were ingested by sea creatures and could enter the circulatory system and cause damage to internal organs. Microplastics collected in the gut and on entering the circulatory system remained there for over 48 days. The researchers were concerned that this could have long-term health and reproductive effects.
3. A 2015 study titled “Microplastics in Arctic polar waters: the first reported values of particles in surface and subsurface samples” was conducted by a team of Amy L. Lusher, Ian O’Connor, and Rick Officer from the Marine and Freshwater Research Centre in Galway, Ireland in collaboration with Valentina Tirelli of the National Institute of Oceanography and Experimental Geophysics (OGS) in Italy. This was the first study to identify the presence of microplastics in the Arctic region. Particles were discovered both near the surface and at a depth of below 6 meters, with a concentration range of 0 to 1.31 microplastic particles per thousand liters. The microplastic either broke away from larger pieces of plastic or was carried from wastewater outlets in coastal regions.
4. In 2019, a team led by Dr. Albert A. Koelmans of the Wageningen University, the Netherlands and colleagues, and Jennifer De France from the World Health Organisation authored a study entitled “Microplastics in freshwaters and drinking water: Critical review and assessment of data quality” which identified 50 studies that existed on the concentration of microplastics in various water sources. In this meta-study, the researchers scored the quality of each paper and suggested best practices for future research. They found only the following four studies that met sufficiently rigorous data collection standards.

Title	Authors	Organization	Methods and Findings
Microplastics in surface waters of Dongting Lake and Hong Lake, China (2018)	Wenfeng Wang, Wenke Yuan, Yuling Chen, Jun Wang	Chinese Academy of Sciences	Took samples to identify microplastic concentration in two lakes in China. Studied physical composition and shape of microplastics. Found concentrations between 900 and 4650 particles per cubic meter and that plastic pollution was partly due to fishing in the area.
Synthetic Polymer Contamination in Bottled Water (2018)	Sherri A. Mason, Victoria G. Welch, Joseph Neratko	Department of Chemistry, State University of New York at Fredonia	Sourced 11 brands of bottled water from multiple countries and tested for presence of microplastics using FTIR spectroscopy and absorption of certain dyes. Found that 93% of the 259 bottles had microplastic contamination present. Findings suggest at least a portion of contamination from the packaging process itself.
Wastewater treatment plants as a pathway for microplastics: Development of a new approach to sample wastewater-based microplastics (2017)	Shima Ziajahromi, Peta A.Neal, Llew Rintoul, Frederic D.L.Leusch	Australian Rivers Institute, Griffith School of Environment, Griffith University, Gold Coast   School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology (QUT), Brisbane	Researchers developed a method to speed up identification of microplastic in treated wastewater. Found 22% to 90% of suspected microplastics were non-plastic, showing that visual inspection may overestimate microplastics. Found that tertiary treatment in wastewater plants reduced microplastics to approximately 0.28 microplastics per liter.
Microplastic Abundance and Composition in Western Lake Superior as Determined via Microscopy, Pyr-GC/MS, and FTIR (2018)	Erik Hendrickson, Elizabeth C. Minor, and Kathryn Schreiner	Water Resources Science Program, University of Minnesota   Large Lakes Observatory and Department of Chemistry and Biochemistry, University of Minnesota Duluth	Microplastic contamination was identified and analyzed in Lake Superior in the United States. Microplastics found despite the region's low population density. Polyethene was found to be the most common type.

What Are The Harms Of Microplastics In Water To Human Health?

The harms of microplastics in water to human health are suggested by some studies to include links to cancer, disruption of stomach functions, inflammation, obesity, neurological damage, induced oxidative stress, cardiovascular disorders, and immunological responses. Research in this field is still in its early stages and it is not clear if these harmful links will be substantiated. The WHO’s take has been sanguine, seeing little impact.

Most studies suggest that microplastic concentrations in water are currently too low to have any significant impacts on humans. The harms of polluted water to human health depend on both hazard (potential toxicity) and amount of exposure.

Toxic substances (chromium and cadmium for example) are found in very small quantities and pose a low level of risk. Science Advice for Policy by European Academies (SAPEA) has warned that if plastic enters the oceans at a faster rate than it is today, this may create health problems in the future. This image shows areas being researched for potential microplastic health impacts.

Professor Kurunthachalam Kannan and Dr. Krishnamoorthi Vimalkumar of the New York University School of Medicine observed that plastic use and obesity have both increased approximately three-fold in the last half-century. According to the WHO, these effects are yet to be conclusively linked as much research comes from studying animals and makes assumptions that do not hold in a human context.

The risks would depend on many factors including microplastic concentrations and the chemical properties and toxic additives released (such as PCBs, PAHs, PBDEs, bisphenol A). Biofilms form as layers of micro-organisms that attach to microplastics. John A Glaser, a researcher at the United States Environment Protection Agency notes that the organisms create a living community and can resemble a “hydrogel”.

Research by Nikolina Atanasova and colleagues at the Institute of Microbiology of the Bulgarian Academy of Sciences showed that biofilms can transport pathogens that could be infectious. According to the WHO, some studies show that biofilms in freshwater can transport pathogens that spread antimicrobial-resistant genes.

The WHO emphasizes that humans have most likely ingested microplastics for many decades, but no significant health effects have been conclusively shown. In humans, the gut is an especially sensitive area but many microplastics that enter are considered inert. The European Food Safety Authority found that more than 90% of microplastics are likely to be excreted and that only 0.3% of microplastics smaller than 150 micrometers may be absorbed.

The WHO has noted that some indirect health effects being explored include the spread of antimicrobial resistance and the effect of poorly treated drinking water supplied to vulnerable populations. Another area of potential concern is soil contamination due to the leaching of chemicals.

Do Microplastics Cause Water Pollution?

Microplastics do cause water pollution in that they are a form of water pollution themselves. They exacerbate chemical pollution in water, as those other toxins can stick to the plastic, causing increased harm to the marine environment. This was noted in a 2011 study by Dr. Anthony L Andrady of the Department of Chemical and Biomolecular Engineering at North Carolina State University

Merlin Isaac of the Institute of Plastics Technology and Balasubramanian Kandasubramanian of the Indian Ministry of Defence published an NIH paper where they estimated that 75,000–300,000 tonnes of microplastics are released annually in the EU alone. This is roughly equivalent to releasing the weight of the RMS Titanic every two months. They found that 54.5% of the microplastics floating in the ocean are polyethylene and 16.5% polypropylene.

A study conducted by Mark A Browne in 2008 demonstrated that microplastics could enter the circulatory system of some aquatic creatures and remain there for over 48 days, potentially having serious health effects in the long term.

In 2016, a UNEP Report listed over 800 species that had been contaminated by microplastics in the water showing that this is a widespread pollution problem. Dr. Madeleine Smith of the Department of Environmental Health and Engineering at the Bloomberg School of Public Health at Johns Hopkins University noted that negative health effects which could affect growth and immunity have been seen in the Japanese medaka fish, mussels, corals, and sea birds. Microplastics may release toxins damaging organs and polluting the food chain.

How Much Microplastic In Water Is Harmful To People?

It is not yet known how much microplastic in water is harmful to people. Since scientists have only recently started collecting data on microplastics in water, the threshold beyond which the microplastic harms of polluted water to human health become threatening is uncertain.

Even though microplastics are present in drinking water, good quality water treatment does reduce the concentration. And as mentioned earlier, the European Food Safety Authority notes that the human body excretes over 90% of ingested microplastics. Negative effects on humans have not been conclusively documented, since humans had already ingested a lot of microplastics before this problem became well known.

Estimates of microplastics consumed via food or drink by each person lie between 0.01 micrograms per day and 8.7 micrograms per day. Naturally, countries that have a higher consumption of seafood are more likely to have consumed more microplastics.

Some estimates of the per capita consumption of microplastics by humans according to Dr. Kannan and Dr. Vimalkumar are shown below.

• Mussels: 123 microplastic particles per year in the UK
• Salt: 37-1000 microplastic particles per year
• Shellfish: 11,000 microplastic particles per year in Europe (as per Dr. Lisbeth Van Cauwenberghe and Dr. Colin R Janssen of the Laboratory of Environmental Toxicology and Aquatic Ecology at Ghent University)
• White Wine: 2563–5857 microplastic particles/l in Italy
• Soft Drinks, Energy Drinks, and Tea: 11–40 particles/l in Mexico
• Seafood: 7 micrograms of microplastic for a 225 g serving (as per EFSA Panel on Contaminants in the Food Chain, 2016)

How To Extract Microplastics From Water?

Microplastics in water are extracted from water effectively by sand filtration, ultra-fine physical membrane filters, and other methods designed to reduce the turbidity (cloudiness) of water.

This is done at varying scales in building-level filtration systems, bottled water plants, and for whole communities at Water Treatment Plants (WTPs) and Wastewater Treatment Plants (WWTPs). Even though these processes for how to filter water weren’t designed specifically for microplastics, they work well because they can remove particles of sizes comparable to or smaller than microplastics. These processes are divided into clarification and membrane processes.

• Clarification, where particles, oil, dirt, and natural organic matter are removed from the water. This involves sending water to settling basins or ponds where solids will either float to the top or settle to the bottom. Often after using chemical agents called coagulants or flocculants which cause the impurities to more uniformly separate. Then can then be easily physically skimmed or removed from the water. Residual particles that remain are removed by using a bed of sand grains to which they can adhere.
• Membrane processes such as osmosis and ultrafiltration, that stop particles larger than a certain size from passing through the microscopically fine pores of the membrane.

These two processes often take place in three stages referred to as primary, secondary and tertiary. The primary stage involves the screening of fine and coarse solids. Secondary treatment is done using microorganisms for digesting unwanted materials that remained in the water. The tertiary stage uses membranes to remove specific pollutants that passed earlier stages.

For bottled water plants, the same methods water treatment plants use to remove microplastics is applied at a smaller scale. Physical filtration (often referred to as micron filtration because their effectiveness is rated in how many millionths of a meter they can filter down to) is a common approach. Reverse osmosis (RO) which involves even finer membranes is sometimes utilized. Though RO is rarely used for natural source bottled waters since regulations in many countries require brands labeled as natural to be clean at the source and remain pure with minimal or no treatment when bottled.

Materials used in water treatment tend to be low cost. operational costs can vary depending on the adsorbent (a substance to which pollutants stick) used. Evgenia Iakovleva, an applied physicist at Aalto University, and Mika Sillanpää of the Department of Civil and Environmental Engineering at Florida International University noted common adsorbents and average costs. For example, activated carbon (€500–€1000 per tonne), iron oxide (more than €1000 per tonne), and activated alumina (€300–€500 per tonne).

Are Water Filters Enough To Extract Microplastics From Water?

Water filters are enough to extract most microplastics from water, but studies revealing they are still found in drinking water mean that they are finding ways in after treatment. Possibly by exposure to microplastic in the air or pipes between the points of filtration and consumption.

Each stage of treatment has different effectiveness in removing microplastics from water. In the research on water treatment plants carried out by Paul U. Iyare et al, primary filtration by itself removed between 32% and 92% of microplastics and averaged 72%.

The primary and secondary stages of treatment together remove more than 90% of all microplastics. Tertiary treatment removes an average of 94% of microplastics, while advanced tertiary treatments are known to be able to remove between 82.1% and 99.9% of microplastic. According to the WHO, membrane filtration can remove 100% of all particles greater than 1 micron in size.

The evidence shows microplastics are still finding their way into tap water after passing out of water treatment plants. Municipal water systems may have entry points where other water enters or leaks where exposure to groundwater or air may allow microplastics in. Even at the very final stages when the water is leaving the tap, exposure to microplastics in the air could enter the water and show up in lab tests.

RO and micron filters that are rated as “absolute” (i.e., nothing should get through up to the size the filter is rated for) should in theory be extremely effective at filtering out microplastics. It is common to use filters as low as 0.2 to 1 micron (millionth of a meter) as the final stage in bottled water plants, where some laboratories only see the practical need to measure microplastics 10 microns long or larger. In theory, this should mean 100% effectiveness.

The overall cleanliness of bottling procedures may give a final way for particles to slip in after filtration. This could be via brief exposure to air at the point of filling, pipes between the filters and the point of filling which were exposed to air, or cleansed with water that had microplastics. It is important for bottling plants to have clean processes to prevent this.