Maybe you’ve whipped up some fried chicken and waffles or golden, crisp-edged pakoras. After enjoying the meal, you’ll have to do something with the leftover oil. Starting with the obvious, you shouldn’t pour it down the drain or into the toilet.

Cooking fats, oils and grease are the main cause of clogged pipes and are among the top contributors to fatbergs, solid masses of waste that form in sewer systems. London’s “total monster” of a fatberg weighed 130 tonnes — ”the same as 11 double-decker buses” — and stretched more than 250 metres.