How many cups of tea do Britons drink a day?

A mixture describes one person who might drink no tea, a little or a lot; mean() turns that into a national total. Then the heat capacity of water says what all that kettle-boiling costs.

One person

Britons split into rough groups: some never drink tea (many children and coffee drinkers), some have a cup or two, and some get through a pot's worth a day. A mixture says exactly that, with a weight for each group.

cups_per_person = {0 per day: 40%, 1 to 2 per day: 30%, 3 to 6 per day: 30%}

cups_per_person =1 [0, 4] day⁻¹ {frequency}

That distribution describes one randomly chosen Briton, which is why its plot has a spike at zero.

Everyone

Multiplying that distribution by the population would treat all 68 million people as making the same choice, so the answer would swing between "nobody drinks tea" and "everybody drinks a pot". The national total depends only on the average person, which mean() gives.

population = 68 million
cups = population * mean(cups_per_person)
cups as million per day

124 million per day {frequency}

What the kettles cost

A cup is about 250 mL, but people fill the kettle well past what they need. Boiling raises water from about 15 °C to 100 °C, at 4.18 kJ per kilogram per kelvin, and an electric kettle puts 80% to 90% of its energy into the water.

cup = 250 mL
overfill = 1.5 to 2.5
c_water = 4.18 kJ/(kg*K)
per_cup = cup * overfill * 1 kg/L * c_water * 85 K / (80% to 90%)
per_cup as kWh

0.056 [0.043, 0.073] kWh {energy}

Averaged over the whole day, the country's kettles draw about a third of a large power station's output:

kettle_power = cups * per_cup as MW
kettle_power * 1 year as TWh

2.5 [2.0, 3.3] TWh {energy}

The UK uses about 300 TWh of electricity a year, so tea takes the better part of a percent of it.

How close is it?

The UK Tea and Infusions Association puts the figure at over 100 million cups a day (UKTIA, 2023). The estimate of 124 million per day agrees.