Cotton fabric is made from yarn spun from the fibres of the cotton seedpod, called a boll. Most of the world’s cotton is grown in India and China, usually on farms that rely heavily on pesticides, fertilisers and intensive irrigation.

Growing 1 kilogram of non-organic cottonlint (the raw cotton fibre) uses about 2,120 litres of water from irrigation, according to Textile Exchange, a not-for-profit group promoting sustainable practices within the industry.

Cotton is generally harvested by machine, then undergoes ginning, a mechanical process that removes the fibres from their seeds.

These fluffy fibres are then subject to a series of processes, such as carding and combing, to smooth and refine them until they are ready to be spun into yarn. The same process is used for making organic cotton fabric.

A Textile Exchange life cycle analysis published last year found organic cotton — which is usually grown using water-conserving practices and without pesticides and fertilisers — had reduced potential for global warming, acidification, soil erosion, water consumption and non-renewable energy compared with conventional cotton production.

Australia holds a relatively small piece of the global cotton pie, producing about 2 million bales a year compared to China and India’s 33 million and 27 million respectively, but it punches above its weight in the environmental stakes, contributing less than a third of a per cent to the country’s agricultural greenhouse gas emissions, according to Cotton Australia.

A 2014 industry report found Australian cotton had increased its water efficiency by 40 per cent over the previous decade and had reduced insecticide use by 89 per cent since the late 90s.

Synthetics such as polyester, acrylic, nylon and elastane are made using fossil fuels.

Polyester is the most widely used fibre in clothing, accounting for nearly half the world’s fibre production, or 63,000 million tonnes each year, according to Textile Exchange.

To make polyester, chemicals from petroleum are liquefied under high pressure and forced through tiny holes. As the liquid is squeezed out the holes, it solidifies into fibres.

These fibres are then drawn out to make them longer and thinner, and then spun into a yarn. Sometimes other processes, such as dyeing, crimping or dulling the natural lustre of the fibre, are involved in these early stages.

While synthetics are usually made from non-renewable resources, some are made from recycled materials, such as polyester made from recycled bottles.

Recycled polyester reduces the need for fossil fuels and diverts plastic bottles from landfill. As technology continues to advance, polyester textile manufacturer could eventually become a closed-loop system, according to Textile Exchange.

But beyond the manufacturing phase, all synthetics, recycled or not, have a longer-term environmental impact while they are being used by you, the consumer.

Every time you wash your polyester clothing, it sheds microscopic fibres that travel into waterways, adding to plastic pollution in our oceans.

Man-made cellulosic fabrics involve taking a renewable material, such as bamboo or eucalyptus, and breaking it down until it can be spun into a fibre in a similar process to synthetics, such as polyester.

Viscose, rayon, Lyocell and bamboo are all types of cellulosic fabric.

On one hand, they use renewable materials instead of non-renewable fossil fuels, and crops such as bamboo don’t require the same volumes of water or pesticides, if any, as cotton.

However, just because a material is renewable doesn’t make it the best for the environment. Textile Exchange said greater transparency is needed to ensure logging for these fibres is not being done in ancient or endangered forests, endangered species habitats or otherwise illegal or controversial ways.

Once the wood has been obtained, the process involved in breaking down the raw material involves toxic chemicals that can affect the surrounding environment and people who work in the factories.

According to Textile Exchange, these substances can remain in the fabric during dyeing and finishing. The high-tech process to spin the man-made cellulosic yarn is also energy-intensive.

Because safety standards and environmental impacts of cellulosic fabrics vary so widely, Dr Vuletich advises consumers seek out manufacturers who are transparent about their processes.

Australia is the largest wool producer in the world, with about 75 million sheep producing about 4.47 kilograms of wool per head, but the fibre holds a relatively small share of global consumption: 1.2 per cent in 2015, according to the International Wool Textile Organisation.

Like cotton (and other textile fibres), wool processing involves many water and energy-intensive phases, including multiple washes to clean the fibre. This process is called scouring, which is how lanolin is recovered.

Australian wool processing plants use water-saving methods such as taking the water from the last rinse to become the first wash of the next batch, said Mr Fergusson.

Further processes — called carding and combing — smooth and refine the fibres prior to spinning into fibre and then weaving or knitting into fabrics. These fabrics may undergo fulling and crabbing, which use heated water to shrink and set the cloth.

Because it comes from animals, wool has environmental impacts at the farming level, including land degradation from overgrazing, soil compaction, erosion and loss of organic matter from the soil.

Deforestation and farms impinging on conservation areas are also problems identified by accreditation body Responsible Wool Standard.

This doesn’t mean wool can’t be part of your wardrobe: the Bureau of International Recycling estimated if each person in the UK bought one reclaimed woollen garment, it would save nearly 1,700 million litres of water and 480 tonnes of dyeing chemicals.

Linen is made from bast fibres — fibres made from the stalk of a plant, usually flax but sometimes hemp (Cannabis sativa).

Creating linen involves a process called water retting to break down the stalk into bundles of fibres, which are then mechanically refined and spun into a yarn.

It’s a thirsty process, but not as water-intensive as cotton processing. Growing these plants is also less intensive terms of water and pesticides than cotton.

Hemp is not a big hitter in the global fashion industry, but has been pointed to as a more environmentally friendly option in the past. Dr Vuletich said that claim mostly stacked up.

But, she added, the fact the cannabis plant was also used as a drug meant it wasn’t as widely embraced as a textile as cotton. Nor had it seen the same investment and innovation to create high-quality yarns.

“It’s always going to remain a niche fibre because of its raw material.”

Even the more widely used flax linen is still a long way behind other fibres in terms of popularity, partly because it has a “particular look”, Dr Vuletich said.

“We don’t all want to wear linen because it crushes so easily, it’s [about] useability.”

No, not a textile, but together with other finishing techniques, dyeing is the most energy-hungry part of the garment manufacture process, according to the Measuring Fashion report, accounting for 36 per cent of the greenhouse gas emissions of the whole process.

The dyes themselves are also affecting the environment.

A recent documentary tracked how chemical waste from dyeing was making its way into waterways. But the spotlight on these practices is already leading to change.

“There’s a zero-discharge initiative that a lot of the brands are realising that they need to really put pressure on suppliers in China around hazardous chemical waste into water,” Dr Vuletich told the ABC last year.

Mr Fergusson, who specialises in dyeing, said when he lived near dyehouses in Indonesia, “the rivers used to change colour” — but other dyehouses nearby treated their wastewater and used it to irrigate rice paddies.

Here in Australia, dyehouses must meet very stringent discharge standards so they usually have an on-site treatment plant, Mr Fergusson said.

The Australian industry is also making strides in new technologies, he said, including a method called cold pad-batch dyeing, which cuts down on energy needs by using cold water.