Tap water is completly safe. Don't worry.

I do not drink water from taps that are [appear to be] fed from a tank. If I'm not reasonably certain that it's from a rising main, I use bottled water.

Avoid drinking water from the bathroom tap of your hotelroom because it might come from a tank. Otherwise, tap water in London is safe to drink.

Do keep in mind though that drinking tap water away from home might lead to an upset stomach or cause other problems.

Like drinking water anywhere away from your home, the taste and smell may be a bit different. To me the water in London has a very different taste than I am used however it is, as all others have said, very safe to drink. And substantially less in price than paying an exhorbitant fee for bottled water.

Wow, 2 people have told us that water from a tank might be unsafe. Where does tank water come from that would make it so?

No, ronw, I think 2 people have expressed a preference for water *not* from a tank.

AFAIK, it is not unsafe to drink any tap water. If it was, there would be signs up saying so.

I don't like the taste of tap water and tend not to drink it, but that is just a personal preference, nothing to do with safety.

Tank water comes from the same source - the Thames - but it may sit there for hours/days, so might not be the freshest. However, Thames water is never the freshest, potentially having been recycled through several pairs of kidneys....

cold water in England,at a kitchen sink comes from the mains and is perfectly safe, the problem is that in some hotels and houses, the mains water goes to a tank in the roof for storage, this sometimes feeds the bathroom taps, this tank may not have a lid and birds etc get in and drown.

Hubby ( a plumber) has taken up to 20 sparrows out of a tank in a roof.

Yes, its perfectly safe.

Regulations stipulate that taps that are not from rising mains be marked as unsafe for consumption - so even in your hotel (if its reputable) you will know if this is the case.

Thanks for the clarification, Peter. I guess I over-reacted to TH13's "otherwise (it) is safe" comment.

So, why would tank water be so prevalent in London that we need to be cautioned about it? Presumably, it is pumped up to a roof-top tank and gravity-fed as needed. I can see the need for that in places where there are frequent interuptions in waterworks pumping stations, but London?