In July 2017, Prigi Arisandi stood in the Surabaya River in East Java, Indonesia, and counted nappies. In one hour, “176 diapers floated in front of my face,” he said.

The Indonesian biologist, who won the Goldman environmental prize in 2011 for his efforts to stem pollution flowing into the Surabaya, decided to make nappy waste his focus. He launched the Diaper Evacuation Brigade, a movement of volunteers who travel across Indonesia, wearing hazmat suits to fish used nappies out of the country’s rivers.

Indonesia produces an estimated 6bn disposable nappies a year. Many end up thrown into rivers and the sea, in part because the country lacks waste infrastructure but also because of a belief among some that burning babies’ nappies could cause them pain. Disposable nappies made up 21% of the waste found in the waterways of 15 Indonesian cities, according to a 2018 World Bank study. In the water, nappies break down into microplastics, leach chemicals, damage marine life and potentially contaminate drinking water, most of which comes from the rivers.

The problem of disposable diaper waste is not confined to Indonesia. While discussions of single-use plastics tend to be dominated by plastic straws and bags, disposable nappies are one of the biggest contributors to plastic waste globally. They are typically made from several types of plastic, including a polyethylene waterproof back layer and a polypropylene inner layer.

A baby may get through 4,000-6,000 nappies by the time they are potty trained. Every year, an estimated 167bn disposable nappies are produced, requiring 248.5m barrels of crude oil. Because of the mix of materials, and the addition of human waste, they are very hard to recycle. The vast majority end up in landfill, where they take hundreds of years to break down. Globally, more than 300,000 disposable nappies a minute are sent to landfill, incinerated or end up in the environment, including the ocean.

The problem is disposable nappies are easy and convenient. Parents may be too overwhelmed to cope with the extra work of reusable nappies, they may lack adequate washing and drying facilities or be put off by upfront costs. As a result, disposable nappy companies’ sales are booming in some regions, particularly south-east Asian countries such as Indonesia, with its rising population and growing middle class.

One alternative is “biodegradable” or “compostable” nappies, which seem to promise a solution to this complex problem: the convenience of a single-use product with less guilt about what happens to it after use.

However, the vast majority of biodegradable or compostable nappies still contain plastic elements, often the sticky tabs or the outer film. “The best example that I could find was made out of around 80% of biodegradable materials,” said Dr Charlotte Lloyd, an environmental biogeochemist at the University of Bristol, who is researching nappies available in the UK.

After using a nappy, Lloyd said, “you tend to roll it up, stick it down, and then actually all of your biodegradable materials will be protected within that outer shell”. When the nappies end up in landfill – which almost all will – the biodegradable materials will have little contact with the oxygen they need to biodegrade. “So you spend more money on a biodegradable nappy, thinking that you’re doing the right thing. But actually, it’s just still sitting in landfill,” she said.

It’s a situation that Laura Crawford, also based in the UK, finds incredibly frustrating. After a thwarted attempt to use reusable nappies with her baby – struggling with a toddler and colicky newborn “[they] were just the last thing I could cope with” – she decided to create an eco range. In 2018, she launched Mama Bamboo, producing nappies from sustainably sourced, FSC-certified bamboo with compostable bioplastic liners.

However, eliminating fossil-fuel plastic is still “only half the answer”, she said. Her nappies break down in hot composters, which few people have, or industrial composters, which are not nationally available in the UK.

“At the moment, we have a system where people are prepared to pay upfront for expensive nappies and then get their government to pay – and the environment to pay – to put them into landfill,” said Dr Mark Miodownik, a materials scientist at University College London. He has been working with Mama Bamboo and other biodegradable nappy companies as part of a research project on establishing a comprehensive industrial composting system for plastics.

Small-scale efforts to create better systems for compostable nappies are popping up across the world. Paris-based social enterprise Les Alchimistes collects compostable nappies from childcare centres and takes them to a composting site on the outskirts of the city. It tests the compost, said Maiwenn Mollet, director of the nappies project, “to check there is no ecotoxicity and also to study microplastics”. Once they have proven the compost’s quality, they plan to sell it to farms. Kim and Jason Graham-Nye, founders of gDiapers, are trialling their 100% compostable nappy in West Papua, Indonesia. They work with an Indonesian company to do daily nappy drop-offs and collections, and to compost the used diapers locally.

Other efforts focus on increasing uptake of reusable nappies. These create less landfill waste but their environmental credentials are not always clear cut. Many are made out of cotton, a thirsty crop often grown with a lot of pesticides. They also require laundering, which can be water- and energy-intensive. Reusables’ footprint depends on how they are used, according to 2008 UK government analysis, which found that line-drying, washing in full loads and using them for subsequent children would make reusables a better environmental choice than disposables.

In the south Pacific archipelago of Vanuatu – where disposable nappies make up 27% of the nation’s rubbish – local social enterprise Mamma’s Laef and UK-based Bambino Mio have been providing modern reusable nappies to 150 mothers. Here, nappies tend to be hand washed and line dried. The pilot has been very popular, said Jack Kalsrap, who runs Mamma’s Laef with his wife, Mary, because “it can be expensive for families to set up buying a pack of reusable baby nappies”.

Arisandi wants to make reusable nappies more accessible in Indonesia, too. He’s calling on the government to crack down on single-use nappies and to subsidise reusable cloth nappies to make the initial costs more affordable. He also wants nappy companies to be forced to take responsibility for the waste their products produce.

Experts globally speak of a lack of policies around disposable nappies. “To date there’s no legislation [in the EU] regulating nappies,” said Larissa Copello, consumption and production campaigner at Zero Waste Europe. The organisation wants incentives for reusable nappies as well as pressure on big nappy companies to make their products more sustainable.

“There definitely is a better route than plastic disposables but, at the moment, the system is just very broken,” said Lloyd, adding, “we’re morally obliged to do something better than we’re currently doing.”