Hot water myths

Here in Britain, most sinks have two taps. Turn one and you get hot water, turn the other and you get cold. It’s barbaric.


Back where I come from, a former British colony on the other side of the Atlantic, most taps are mixed. Instead of washing your hands with water from either Satan’s bathtub or Jack Frost’s kiddie pool, you can get water of any temperature. It’s positively refined.


It’d be easy to assume that Brits were just being backward (it wouldn’t be the first time) or that they were inflicting themselves with unnecessary annoyance as a character-building exercise (again, not the first time).

But they’re actually being safe, or so says Tom Scott:

You see, as Tom Scott explains, hot water tanks used to be largely unsealed contraptions on rooftops or in attics where the water might sit for a long time before being used. Apparently there was no requirement to keep hot water drinkable. Cold water, on the other hand, would come straight from the city and had to be kept to a drinkable standard.

From what I can find though, that changed in 2010. The new regulations say:

There must be a suitable installation for the provision of heated wholesome water or heated softened wholesome water to: (a) any washbasin or bidet provided in or adjacent to a room containing a sanitary convenience; (b) any washbasin, bidet, fixed bath and shower in a bathroom; and (c) any sink provided in any area where food is prepared.

Wholesome water is basically water treated to a standard considered safe to drink and the only real difference in regulations between hot and cold water is the word “heated”. In any bathroom or kitchen in the UK, hot water must be drinkable.

So there’s no reason to avoid mixer taps or to think the hot water in Britain might not be safe, not even strange old-school legal ones.

With that in mind, I’m left wondering why British people insist on filling their kettles with cold water. It seems more efficient to me to start with hot water and heat the kettle to boiling from there, but I have been the recipient of too many gasps of surprise and disdain to even think of filling my kettle with hot water in polite company.

[Digression: I have a theory about why tea and other hot drinks are more popular in the UK than in North America. It has to do with voltage. With double the voltage (220V compared to 110V), water takes half the time to boil. Faster tea means more tea.]

The rationalization the Brits give me is that the hot water is unfit for human consumption, but we now know that’s not true. But they aren’t being totally daft. There are good reasons why you might want to start with cold water. Or are there?

Some people say that cold water has a higher oxygen content. It is true that as temperature increases, oxygen solubility in water goes down, but at boiling point it hits zero. So no matter what temperature you start at, by the time you’re ready to make that cuppa, there won’t be any oxygen left dissolved in your water. Busted.

The other reason people give is that hot water can pick up more sediment. Again, while technically true, this is a bit misleading considering the legal requirement that all water coming out of British taps (hot or cold) be wholesome. The amount of sediment in your water will be much more dependent on geography than on temperature. Water hardness is such a big concern here that some teas are even specially blended for hard or soft water.

There doesn’t seem to be any good reason to avoid using the hot water tap or to insist on having two separate taps. In this, at least, the Brits are wrong.

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