What Happens to Microplastics When You Wash Synthetic Clothes?

Every time you wash a load of synthetic clothing — polyester, nylon, acrylic, elastane — hundreds of thousands of tiny plastic fibres shed from the fabric and wash down the drain. These microfibres are now recognised as one of the largest sources of microplastic pollution in the world’s oceans.

For UK consumers, understanding how this happens and what you can do about it is one of the most impactful steps in reducing your personal microplastic footprint.

The Scale of the Problem

A study published in Nature Communications estimated that between 200,000 and 500,000 tonnes of microplastic fibres enter the world’s oceans annually from textile washing — making it one of the single largest sources of ocean microplastic contamination.

Research by the University of Plymouth found that a single domestic wash load of synthetic textiles can release up to 700,000 microplastic fibres. These fibres are too small to be caught by most washing machine filters, pass through wastewater treatment plants, and end up in rivers and oceans.

A 2020 study by the International Union for Conservation of Nature (IUCN) identified synthetic textiles as the largest source of primary microplastic pollution in the ocean, accounting for approximately 35% of all microplastics released into marine environments globally.

What Happens to the Fibres?

When synthetic clothes are washed:

1. Mechanical agitation in the drum loosens fibres from the fabric surface
2. Water and detergent carry the fibres into the drainage water
3. Wastewater treatment captures some fibres (UK treatment plants typically remove 80-95% of microplastics), but the volume is so large that the remaining 5-20% represents millions of fibres per treatment plant per day
4. Treated effluent carries surviving fibres into rivers and eventually the sea
5. Sewage sludge — the captured fibres end up in sludge, which in the UK is often spread on agricultural land as fertiliser, returning the microplastics to the terrestrial environment

According to research by the Rivers Trust, UK rivers contain significant quantities of synthetic microfibres, with concentrations highest downstream of wastewater treatment plant outfalls.

Which Fabrics Shed the Most?

Not all synthetic fabrics shed equally:

• Polyester fleece is the worst offender — the brushed surface creates loose fibres that shed readily. A study in Environmental Science & Technology found that a single fleece jacket can shed up to 250,000 synthetic fibres per wash.
• Acrylic knits also shed heavily due to their loose knit construction
• Nylon sheds less than polyester but still releases measurable quantities
• Tightly woven polyester (like athletic wear) sheds less than loosely knit or brushed fabrics

Natural fibres — cotton, linen, wool, silk, hemp — also shed fibres during washing, but these are biodegradable and do not persist in the environment as microplastics.

What UK Consumers Can Do

Wash Synthetic Clothes Less Often

The simplest intervention. Many synthetic garments (fleeces, outdoor jackets, gym wear) do not need washing after every wear. Spot-cleaning and airing between washes significantly reduces the total number of wash cycles and therefore the total fibre release.

Wash at Lower Temperatures

Research shows that lower wash temperatures reduce fibre shedding. Washing at 30°C rather than 40°C or higher reduces both microfibre release and energy consumption.

Use a Microfibre-Catching Device

Several products exist to capture microfibres during washing:

• Guppyfriend wash bag — a mesh bag that captures microfibres during the wash. Place synthetic garments inside the bag before putting them in the machine. Studies have shown it captures a meaningful proportion of shed fibres.
• Cora Ball — a ball that goes in the drum and attracts microfibres through a bio-inspired design
• Washing machine filters — external filters that attach to the machine’s drain hose. Some newer washing machines include built-in microfibre filters, and France has legislated that all new washing machines sold from 2025 must include microfibre filters.

Choose Natural Fibres When Possible

When buying new clothes, consider natural-fibre alternatives:

• Merino wool replaces polyester base layers for warmth and moisture management
• Organic cotton replaces polyester and poly-cotton blends for everyday wear
• Linen is excellent for summer clothing
• Hemp is durable and biodegradable

These materials still shed fibres during washing, but the fibres are natural and biodegradable — they do not persist in the environment as microplastics.

Avoid Fabric Conditioner

As discussed in our laundry products guide, many fabric conditioners contain fragrance microcapsules — tiny plastic shells that are themselves a source of microplastic pollution. Skipping fabric conditioner eliminates this additional source.

The UK Regulatory Landscape

The UK government’s Environmental Audit Committee has examined microfibre pollution from textiles. While no specific legislation exists in the UK requiring washing machine filters (unlike France), the committee has recommended further research and potentially regulatory action.

The EU’s proposed Ecodesign for Sustainable Products Regulation includes provisions that could require textile manufacturers to reduce microfibre shedding — which would affect products sold in the UK market.

Sources

1. Microplastic fibres from textiles reaching the ocean — Nature Communications, 2020
2. Release of synthetic microplastic fibres from domestic washing machines — Marine Pollution Bulletin, 2016
3. IUCN primary microplastics in the ocean — IUCN, 2017
4. Microfibre release from fleece jackets — Environmental Science & Technology, 2016