Microplastics in drinking water: which filters really remove them?

Microplastics are now commonly found in both drinking water and bottled water, but their amount can be significantly reduced with suitable filtration. However, not all filters are equally effective. In this article, you will learn which technologies really work, what their advantages and disadvantages are, and how to choose a filter that protects your health without unnecessarily burdening your pipework.

What are microplastics and how do they get into drinking water?

Microplastics are tiny plastic particles ranging in size from 1 μm to 5 mm. Smaller particles below 1 μm are often referred to as nanoplastics. Unfortunately, they are now found virtually everywhere – in the oceans, on mountain peaks, in soil, food, air, drinking water, and even directly in the human body.

Microplastics enter drinking water mainly through the breakdown of plastic waste in the environment, such as PET bottles or plastic packaging. They can also get into water during the washing of synthetic materials, which release tiny fibres. In the past, they were even a common ingredient in some cosmetic and cleaning products, although their manufacture for these purposes is now being gradually restricted in the EU.

And how is it possible that microplastics are also present in tap water? Conventional wastewater treatment plants can capture larger pieces of plastic, but huge quantities of tiny microplastics pass through the treatment process and continue into rivers and reservoirs that serve as sources of drinking water.

Microplastics are everywhere today

So is drinking bottled water better?

No, unfortunately drinking bottled water is not the solution either. It contains microplastics released from the bottle in which it is stored, and in fact in much higher quantities than tap water. Scientists from Columbia University and Rutgers University in the USA carried out a detailed study in which they analysed bottled water samples. They found that the average litre of bottled water contains approximately 240,000 particles of microplastics and nanoplastics.

Are microplastics in drinking water dangerous to health?

There is growing evidence that microplastics may pose a health risk. However, the exact effects of long-term exposure on humans are still the subject of intensive research.

What we do know for certain is that microplastics bind toxic substances, such as pesticides, organic pollutants and heavy metals. Once ingested, these substances may have negative effects on the health of both humans and animals. In addition, microplastics can cause oxidative stress in cells, which is a form of cellular toxicity and a risk factor in the development of certain chronic diseases.

Research by the Institute of Hydrodynamics of the Czech Academy of Sciences, which focused on the occurrence of microplastics in various water supply sources and in filtered drinking water, showed that:

• Microplastics were present in all analysed samples, at concentrations ranging from several dozen to several thousand per litre of raw water, and from single figures to hundreds of particles per litre of treated (drinking) water.

• The reduction in microplastics between raw and treated water reached 70–88%. The vast majority, up to 95%, consisted of microplastics smaller than 10 µm.

• The material composition was dominated by commonly used plastics such as PET (polyethylene terephthalate), PP (polypropylene) and PE (polyethylene), but also cellulose acetate (CA) and polyvinyl chloride (PVC).

For this reason as well, the EU adopted a directive which, for the first time, introduces a framework for monitoring microplastics in drinking water. The directive does not yet set any binding hygienic limit, but it does require their inclusion on the so-called watch list.

Which water filters really remove microplastics?

While drinking bottled water can paradoxically increase microplastic intake, filtering drinking water does make sense. But which technology should you choose? The most suitable option is mechanical or membrane filtration, which captures unwanted particles; a carbon filter can also help to some extent. Other water treatment methods are ineffective against microplastics.

Membrane water filters differ in pore size, while mechanical filters differ in mesh fineness. In both cases, this parameter is stated in μm (micrometres) and determines the size of particles the water filter is capable of capturing.

However, be careful: for drinking water, smaller pores do not automatically mean better filtration – extremely small pores will indeed capture even the smallest nanoplastics in water, but they will also remove essential minerals from drinking water. A typical example of such a filter is reverse osmosis – water treated in this way differs significantly in composition from drinking water and may paradoxically cause health problems for consumers.

Table: Comparison of drinking water filtration technologies.

Which water filters are ineffective against microplastics and why?

There are many myths surrounding drinking water filtration, often spread by sellers themselves, so we have also prepared a list of filters that will not remove microplastics from water.

Will a water filter jug help with microplastics?

Only to a limited extent. Water filter jugs usually work on the principle of carbon filtration, which captures dissolved harmful substances but has little effect on mechanical contamination. There are also special filter jugs with a membrane, but these usually do not have sufficiently small pores and will not capture the smallest particles. In addition, filter jugs are often made of plastic and therefore may release further microplastic particles into the water.

Filter jugs are therefore primarily intended to remove chlorine and improve the taste and odour of water, not to remove microplastics.

A filter jug improves the taste and odour of water, but it cannot deal with microplastics

Will boiling or a UV lamp remove microplastics?

No. Boiling and UV lamps are water disinfection methods that remove harmful microorganisms, viruses and bacteria. They are completely ineffective against mechanical contamination. On the contrary, high temperatures may cause some plastics to release more harmful chemical substances.

Is activated carbon enough?

Partially. A water filter with activated carbon physically captures microplastics by adhesion to its extremely porous surface, so rather randomly. For reliable microplastic removal, it is advisable to combine it with membrane filtration.

Which microplastic filter do we recommend for the home?

If you want the assurance of clean water free from microplastics and other mechanical contamination, we recommend two-stage filtration:

1. A pre-filter with a 20 μm to 100 μm mesh, installed at the inlet. This captures larger impurities and thus protects both the water pipework and the downstream tap filter. A finer whole-house water filter is not suitable, as it could cause pressure losses in the pipework and would require frequent maintenance.

2. A tap filter with a 0.1 μm to 1 μm cartridge, installed under the sink. In this way, you can purify water intended for drinking and cooking even from the smallest particles, without burdening the entire domestic pipework.

As a pre-filter, for example, the lead-free Honeywell F76S-LF sediment filter has proved effective for well water. Its 20 µm filter element captures sand, fine sediment, rust fragments and plastic particles. The filter features backwashing, which allows quick and efficient cleaning of the mesh without the need to interrupt the water supply during maintenance.

However, if your water is more heavily contaminated, we recommend installing a coarser filter at the inlet so that it does not clog unnecessarily often or reduce pressure in the pipework. One solution may be the Honeywell HS10S-LF domestic filtration station with a 100 µm filter element.

Before choosing a specific filter, we always recommend that our customers arrange an independent laboratory water analysis. Only then will you know what types of impurities the filter should be able to handle. No water filter is universal or the best in every case, and a household water treatment and purification system should always be designed to suit the specific application.

Honeywell domestic filtration station

How should a domestic water filter be maintained and when should the cartridge be replaced?

No filter can do without careful and regular maintenance. The procedure differs depending on whether it is a mechanical or carbon filter. Below we describe the general maintenance steps, but you should always follow the manufacturer’s instructions.

Mechanical water filter maintenance step by step

A mechanical filter contains a mesh that captures solid particles in the water. These impurities gradually accumulate in the mesh. If they are not removed, the flow rate will begin to decrease and may eventually lead to complete blockage.

The maintenance interval is individual, but in general the finer the filter, the more frequent the maintenance, and cleaning should be carried out at least once every six months. However, if you notice signs of clogging, especially reduced flow rate, clean the filter immediately.

1. Close the valves before and after the filter.

2. Carefully remove the mesh from the filter and rinse it under running water. Do not use brushes, sponges or cloths.

3. Return the mesh to the filter and open the valves.

Some mechanical filters feature backwashing or automatic flushing, which makes maintenance easier.

Carbon filter maintenance step by step

A carbon cartridge has a limited service life of around 6 months. After that, it is no longer able to capture further impurities. Replace the filter cartridge at the intervals specified by the manufacturer, or sooner if you notice a deterioration in water quality.

Looking for effective drinking water filtration? Contact our specialists, who will design a system tailored precisely to your needs: poptavky@bola.cz, 311 257 435.

Frequently asked questions about microplastics in water

Does reverse osmosis remove microplastics from water?

Yes. Reverse osmosis is one of the most effective technologies for removing both microplastics and nanoplastics. At the same time, however, it also removes most mineral substances from the water, which is why it is not a suitable solution for households.

Is tap water worse than bottled water when it comes to microplastics?

No. According to studies to date, bottled water generally contains more microplastics than mains water, because particles can be released from both the plastic bottle and the cap. If the quality of tap water is satisfactory, it is usually the better choice in terms of microplastics.

Will a filter jug help with microplastics?

Only to a limited extent. Standard filter jugs are designed primarily to improve the taste of water and remove chlorine or certain dissolved substances. They are usually not sufficiently effective at capturing fine microplastics and nanoplastics in water.

How can I tell whether a filter is really effective against microplastics?

Pay particular attention to the filtration type and the pore size or filtration fineness stated by the manufacturer. To capture microplastics, mechanical or membrane filters with a fineness of approximately 0.1 to 1 µm are suitable. It is also an advantage if the manufacturer supports the filter’s effectiveness with results from independent laboratory tests.

Do I need a different filter for well water than for mains water?

Often yes. Well water may contain higher levels of sediment, iron, manganese or microorganisms, so it usually requires a different combination of filters than water from the public mains supply. The right solution should always be based on a laboratory analysis of the specific water source.