How pure is the water from your tap? – BBC Radio 4

A recent study on how to get rid of microplastics in water sparked presenter Marnie Chesterton’s curiosity. When she turns on the tap in her kitchen each day, what comes out is drinkable, clean water. But where did it come from, and what’s in it? Dr Stewart Husband from Sheffield University answers this and more, including listener questions from around the UK. Is water sterile? Should I use a filter? And why does my water smell like chlorine?

Also, new research indicates that bumblebees can show each other how to solve puzzles too complex for them to learn on their own. Professor Lars Chittka put these clever insects to the test and found that they could learn through social interaction. How exactly did the experiment work, and what does this mean for our understanding of social insects? Reporter Hannah Fisher visits the bee lab at Queen Mary University in London.

And finally, more than 20 million years ago, our branch of the tree of life lost its tail. At that point in time, apes split from another animal group, monkeys. Now, geneticist Dr Bo Xia at the Broad Institute of MIT and Harvard thinks he may have found the specific mutation that took our tails. Marnie speaks with evolutionary biologist Dr Tom Stubbs from the Open University about why being tail-less could be beneficial. What would a hypothetical parallel universe look like where humans roam the earth, tails intact? And what would these tails look like?

Presenter: Marnie Chesterton Producers: Louise Orchard, Florian Bohr, Jonathan Blackwell, Imaan Moin Editor: Martin Smith Production Co-ordinator: Jana Bennett-Holesworth 

BBC Inside Science is produced in collaboration with the Open University.