[chris (OP)]

We are comfortable washing up in the stuff, and even washing ourselves with it, but are we not supposed to cook with or drink the water out of the hot tap? Would it not make good energetic sense to fill the kettle from the hot tap and thus save electricity or gas because then you wouldn't need to raise the temperature of the water by so much?

Chris

[JP]

It would indeed save energy to do that.  I think the primary concern is that things dissolve more quickly in hot water than in cold, so if there's any contaminants in your pipes, you'll end up drinking more of it using the hot water.

[graham.d]

I think a reason is that in the UK the hot water supply has often been supplied, along with the cold water except for the main kitchen tap, from a storage tank in the loft. There is a risk of various unpleasant things getting into this tank, which often has no cover or, at best, a loose sheet of expanded polysyrene. The plumbing industry in the UK is very slow to adopt new practices, but more modern systems are mains pressurised and sealed. I don't think there should be a problem then.

[Geezer]

It should. The concentration of minerals might be slightly lower because the water heating system tends to precipitate minerals, although I'm not sure what effect the water temperature might have on killing any bacteria.

However, it depends on your system. In the US, the water heater is sealed and operates at the same pressure as the water main (which is why showers actually work in the US.)

That may not be the case in the UK. In the houses I lived in in Scotland, the hot water tank was fed from a cistern in the attic, so there was an enormous difference between the cold and hot water pressures, which is why it was virtually impossible to have a shower.

Not only that, in my parents house, on one occasion the hot water ceased to flow entirely. Being the youngest member of the family, I was sent up the the attic to investigate. I discovered that a sparrow had drowned in the cistern and its remains were blocking the flow of water from the cistern to the hot water tank!

(I think Graham made the same point)

[doppler1]

I can advise that cold water is also vulnerable to infiltration by beasts and bugs as it is also usually stored at some point. I think that if you use hot water to fill your kettle up you should be quite OK because you are still going to boil the water which should kill any nasties anyway. Even in Africa, we use sealed water heaters at the same pressure as the cold water inmost built up areas and the supply is exactly the same to both systems which means that both have been treated with chlorine and other goodies to prevent the growth of the regular bad guys. In essence, there would not be much difference on our end as far as risk is concerned but the hot water does seem to taste a little different which plays a psychological game I guess on the consumers mind....why does it taste so different??

[rosy]

According to graham, UK houses have open storage tanks in the attic?  I find this surprising.  Is this true?

Yup. Absolutely true. But the kitchen tap is fed directly off the mains. Hence drinking from either the hot tap, or the bathroom cold taps, is a bad plan.

[Variola]

My ex-in laws noticed their hot water smelt funny. Examination of the boiler turned up nothing, so they went up into the loft investigate.
They found 2 dead mice and a rat floating about in it...  [xx(] [xx(]

Moral of the story is

*Keep your cold water tank covered!
Water in the bathroom is often from the cold water tank too, so be careful next time you brush your teeth!!

[Bored chemist]

It predates WWI
The tank means you can get away with a smaller mains pipe- the pipe only has to supply the average needs because the tank provides the peak flow. It also means that if the mains fails you still have water and it makes it impossible for anything to contaminate the mains system from the household system.
The reason many showers work in the UK is that both the hot and cold water are supplied by a tank in the roof, so the hot and cold water pressures are nearly equal.
The problem is in houses (like mine) where there isn't a cold water tank and the cold water is fed directly from the mains at much higher pressure than the hot water from the tank.
You can get pressure equalising valves for this or you can rely on a tremendously powerful computer running a feedback system.  Since the computer concerned is the human brain, showers in the US have to depend on something else. The rest of us just throttle the cold water back a bit.

[RD]

Why go to the extra trouble (and danger) of a tank and separate water system?  Why not just use the regular water system? 

Having a cold water tank in the loft does help safeguard against your boiler going boom if the water supply was interrupted. [Particularly if you have a 'solid fuel' fire heating it ... http://www.hse.gov.uk/services/localgovernment/boilers.htm].

[neilep]

Can I drink the water from the tap in my garage ?

[Geezer]

The problem is in houses (like mine) where there isn't a cold water tank and the cold water is fed directly from the mains at much higher pressure than the hot water from the tank.
You can get pressure equalising valves for this or you can rely on a tremendously powerful computer running a feedback system.  Since the computer concerned is the human brain, showers in the US have to depend on something else. The rest of us just throttle the cold water back a bit.

I think this also tends to explain why people in the UK tend to prefer baths to showers. I've heard some people there even have one more than once a week  []

[Geezer]

Can I drink the water from the tap in my garage ?

Only if it comes blasting out of the tap at mains pressure. Also, if it's been there for a long time, it might be fed by a lead pipe.

BTW - a question - would the house plumbing systems in the UK have anything to do with the fact that a lot of the water is supplied from reservoirs? Where I lived in Scotland, the mains water pressure was very high.

[neilep]

Can I drink the water from the tap in my garage ?

Only if it comes blasting out of the tap at mains pressure. Also, if it's been there for a long time, it might be fed by a lead pipe.

BTW - a question - would the house plumbing systems in the UK have anything to do with the fact that a lot of the water is supplied from reservoirs? Where I lived in Scotland, the mains water pressure was very high.

It does come blasting out and having empirically tested it on the family...I will now assume it's safe for me to drink.

[Geezer]

It does come blasting out and having empirically tested it on the family...I will now assume it's safe for me to drink.

I'm surprised you didn't make a great big jug of homemade lemonade with it and take it round to your neighbour as a peace offering.

[...lets split up...]

"Geezer" sounds like "Geyser" and he's on the hot water post, ha ha. I'm so funny today.

[doppler1]

All of our piping downstream of the geyser is copper and much of the upstream is HDPE. We have very few lead pipe systems left. I take it for granted that 99% of the time, it is safe for us to drink right out of the tap and once the piping system leaves the reservoir the system is completely sealed from the environment and therefore any critters. The tricky bit comes at the reservoir and ensuring that nothing gets in there. I used to design water systems and deal with water reticulation control valves and was called out to solve some mysterious valve behaviour on the discharge side of the reservoir. The reservoir was really in the sticks and was used to feed a mining operation so luckily not very many people but they were complaining of pressure surges and that the water was really sweet for the last month or so. Upon opening the valve we found that a baboon had obviously drowned in the reservoir and gone into the piping system when the tank was really low....not a pleasant site. Surprisingly, nobody got really ill at all. Just thought I would share another horror story about water systems

[Bored chemist]

A quick look at a few DIY stores suggests 4 gallon 25, and 42 gallon tanks are common.

[Hongster]

Reading the entries - I had forgotten about the "old system" of having a cold water tank sitting on the roof or in the loft - we used to have it in Johannesburg (South Africa), where my mother still resides... in a suburb called Brixton!

The water pressure was awful - if someone ran a bath downstairs, no one else in the house could get water... imagine if we had tried to fit a shower!

I just thought that in most of our (South African)homes now, we have electric (and solar) geysers fitted, which are pressurised and fed by the cold water mains... so in essence I suppose these modern systems should be fine for cooking and boiling.

Incidentally, I did recently cook up a pack of spaghetti using the water from the hot water tap - no problem whatsoever.

[latebind]

I've been using hot water in the kettle for years.


-Also - When you shower, turn the water off while you are cleaning yourself with the soap, and then turn the water back on to wash the soap off  - this can halve your shower water easily.

[rosy]

-Also - When you shower, turn the water off while you are cleaning yourself with the soap, and then turn the water back on to wash the soap off  - this can halve your shower water easily.

Hmm. Not always true, it depends on your model of shower. Ours is an electric heated type, and runs cold every time it's turned off, so unless I'm washing my hair (which comes down to my waist) I generally spend less time in total running the shower if I don't turn it off to soap myself and then have to wait until it gets back up to warm (usually via far too hot).