As the mercury soared over the weekend, the national press were getting hot under the collar about the latest nefarious deeds of Britain’s endlessly cynical supermarkets. Tesco and Asda were the guilty parties, for daring to charge shoppers the princely sum of 17p for a two-litre bottle of Everyday Value or Smart Price water.

That might sound like decent value if you’re sweltering in the afternoon sun and not in spitting distance of a tap. But for the Daily Mail it was practically robbery. In much the same way that any hotelier with a moustache is instantly dubbed the real-life Basil Fawlty, Tesco and Asda were likened to Del Boy’s ‘Peckham Spring’ ruse from Only Fools And Horses.

Of course, neither retailer was trying to pass off the products as ‘spring water’ or anything of the sort. Surely few shoppers imagined they were getting two litres of elixir from the Fountain of Youth for their 17p. And Daily Bread would argue that’s actually a very fair price for the convenience of a bottle on a hot day.

The mults took a different tack, pointing to the various filtering processes their water apparently undergoes, Tesco amusingly claiming to sell “a wide range of waters to suit all tastes and budgets”. Asda, meanwhile, argued that its water was cheaper than buying a £16 Brita water filter and using it for the recommended 40 gallons (21p for two litres). Its argument was only slightly undermined by the fact it sells a Brita filter for £11 on its website.

Today Sainsbury’s stuck its oar in. “Keep cool and carry on,” the supermarket mischievously advised fans on Facebook page, before linking to the Mail’s story. “Rest assured our Basics range of still and sparkling bottled water is genuine spring water. Just in case press speculation about some other supermarkets had you wondering…”

That’s what an extra 3p a litre will buy you. Meanwhile, rumours of a return to UK shelves for Dasani are as yet unconfirmed…