According to recycling charity Wrap, an estimated three billion nappies are thrown away every year in the UK. Concerns over plastic waste and a want to save money have been driving a rise in the popularity of reusable nappies but, as listener Amy asks, are they really better for the planet, and your pocket?

Me and the team speak to Wendy Richards, also known as The Nappy Lady. She runs one of the biggest nappy advice and sales websites specialising in reusables. Crunching the numbers with her we look at the complete financial costs of both reusable and disposable nappies, even taking into consideration the extra washing costs needed to clean reusables.

But what about the environmental impacts of reusable nappies. Are they really better than disposables when you factor in the energy and water used to clean them? That's what we ask Professor Rob Holdway from Brunel University and Giraffe Innovation. Giraffe Innovation recently completed a thorough study - commissioned by DEFRA, the government’s Department for Environment, Food and Rural Affairs - looking at exactly this.

Once again this series we’re testing and investigating your suggested wonder-products, so if you’ve seen an ad, trend or fad, and wonder if there’s any evidence to back up a claim, drop us an email to sliced.bread@bbc.co.uk or you can send us a voice note to our WhatsApp number: 07543 306807.