A Guardian reader asked the following question of Leo Hickman last year: “Watching those pictures of water being pumped out of flood-stricken areas got me thinking: how much energy does it take to produce all our mains water?”

It’s a good question. And he tackled it like the expert he is.

Everyday the UK uses 19 billion litres of tap water, and in one year the figure is seven cubic kilometres. Between 2% and 3% of the UK’s electricity is used to process and ‘deliver’ this water to UK homes, and this creates 0.5% of its carbon emissions. Hickman’s conclusion was that a litre of water has a footprint of 0.298 grammes, and said “even if you had one very full bath - about 150 litres - every day for a year, overall it would represent just 15kg of greenhouse gas emissions. That’s about what the average car produces over 80 kilometres.”

What does this tell us? We’re not sure. But it was an interesting read all the same.