Today, three and a half years after leaving the UK, I finally learned why they have separate taps for hot and cold water. Well, actually, I read two separate explanations that both make sense, but I don’t know which one it really is.
(1) Fluctuating pressure. Mains water pressure can be unreliable in parts of the UK. Hot water coming (with constant pressure) from a hot water tank in your house, mixed with cold water (at variable pressure, especially if someone nearby flushes a toilet) from the water mains can lead to dangerous fluctuations in temperature.
(2) Hygiene regulations. Water in a hot water tank is not boiling and germs could start breeding. If you keep the hot and cold water strictly separate, you can be sure that the cold water (which you use for drinking after all) cannot get contaminated. So mixing mains water and cistern water was actually forbidden in the UK.
By now of course there are taps in the UK that mix the two, but retrofitting all old houses with new taps, new sinks (with one hole instead of two) and possibly new plumbing, too, would be too expensive compared to the limited benefits.
I do not agree, I live in a new development and have separate hot and cold taps in toilets, but mixers in Kitchen and showers. separate hot and cold taps are pain in the backside and these are still being sold in stores alongside mixers. The only reason I have found so far is that the separate hot and cold sink and taps are quite cheaper than mixers.
About the hygiene in mixer taps, I wonder why the hell rest of the world is drinking contaminated water.
Really? They still put in sinks with separate taps in new flats? Wouldn’t have thought that.
As for the hygiene argument, I’ve tried to find out how the rest of the world manages to not die but I haven’t succeeded. UK web sites are full of talk about the dangers of backflow (just Google for it!) but I have found nothing similar on Swedish sites. I haven’t even been able to find the technical term for backflow in Swedish.
It is possible that this is not a problem in other countries. Mains water systems in parts of the UK do have pressure problems, and it is not uncommon (I gather) for hot and cold water to have different pressure, which compounds the problem.