The Big Toilet Project, which will be run by a team of researchers from UCL, is inviting parents and care givers to help them explore why the average toilet training age of children has risen and how to reduce the environmental burden of disposable nappy waste.
Globally, more than 300,000 disposable nappies are sent to landfill, incinerated or are dropped in the environment every minute. With an increasing global population that number is set to rise, but another recent development is also contributing to this mountain of plastic waste.
In many countries the average toilet training age of children has increased by 32%, from 28 months in the 1950s to 37 months in the 2000s. This means that the number of disposable nappies per child has increased, though what is causing this increase remains unclear.
In the UK there has been public outcry and debate about the large number of children who start school (usually at age 48 months) while still wearing nappies. This has led to 'potty shaming', parent blaming, and debates on school policy around nappy changing.
But without information about the causes of changing toilet training practices, finding solutions has been challenging.
The Big Toilet Project will be run by the UCL Plastic Waste Innovation Hub, a team of researchers, designers and engineers exploring issues of plastic waste.
It is the first global initiative that aims to understand people's practices and techniques for toilet training children, to determine what works best for children, parents, schools and the environment, and the reasons why.
Professor Mark Miodownik, lead researcher on the Big Toilet Project from UCL Mechanical Engineering and UCL Plastic Waste Innovation Hub, said: "I understand this is a sensitive and difficult issue for many families. I found toilet training my kids very difficult. We are doing this research because there is a potential 'win-win-win-win' situation here. Finding effective and safe ways to toilet train children earlier helps the child, helps the parents, reduces costs to the family, and reduces plastic waste."
For the first part of the project, the team is inviting people from around the world to take the Big Toilet Project survey and share their toilet training experiences via the project website. Anyone who is currently toilet training their child can take part, whether they at the beginning, middle or end of the process.
The second (optional) part of the project invites parents to complete a toilet training diary, a monthly record of how children's toilet training is progressing.
Dr Ayşe Lisa Allison, a behavioural scientist from UCL Plastic Waste Innovation Hub and the UCL Centre for Behaviour Change, said: "One of the reasons we are gathering information on toilet training is to understand what kinds of behaviour change might help reduce nappy waste.
"We all have a role in shaping a caregiving culture and environment that enables less wasteful practices, whether that's improving acceptance of and access to reusable and recyclable products, or reducing overreliance on nappies by empowering caregivers with the confidence, time, and resources to support toilet training. If it takes a village to raise a child, it takes a village to tackle nappy waste too!"
Data gathered from parents will be combined with a materials systems analysis to explore ways to support parents and kids, reduce environmental waste and grow the economy. Initial results are expected by summer 2025.
Dr Elze Porte, a materials and design researcher from UCL Mechanical Engineering and UCL Plastic Waste Innovation Hub, said: "The engineering that goes into nappies is absolutely fantastic, they are super absorbent and help us provide essential care for children. But to see a mountain of nappy waste and know that we will lose all of these materials by burning them or putting them in landfills is troubling.
"The information we hope to get from the Big Toilet Project will go a long way to helping us figure out solutions, to be very intentional about when and how we use materials."
As part of this UKRI/EPSRC funded project, the research team are also investigating new ways of recycling and composting nappies using enzymes and bacteria.
All of this work is underpinned by a life cycle assessment approach to engineering, which quantitatively assesses the environmental impacts of a product throughout its lifetime, from creation to use to disposal.
Dr Gema Amaya Santos, a life cycle analyst from UCL Chemical Engineering and UCL Plastic Waste Innovation Hub, said: "The mountain of nappy waste facing our planet demands urgent action. While the challenge is significant, it's not unsurmountable.
"Life cycle assessment is key to meeting this challenge because it reveals the environmental hotspots in the nappy lifecycle, allowing us to understand the implications of different changes within the system, pinpointing the impact of potential solutions."
