Is it ok if the hot and cold water both come from the same tap?

[SHsheff]

I dimly remember that hot and cold water supplies in the kitchen should be separate, even if they emerge from the same tap.

 

However, I am now told that it's ok as long as there's a combi boiler heating the hot water as this is effectively mains water.

 

Can anyone confirm that this is so? Presumably there's no need to run the cold water before drinking it?

[Rand Hobart]

When we did out our kitchen 10 years ago, you practically couldn't buy a non mixer tap for the sink. If you look at the pipes they only come together for the last couple of inches before the tap. We have a conventional boiler so we run the cold for a second before using it for drinking . I used to feel a bit guilty about it until there was a leak in the lane outside our house and I reported it. It took the water company 3 months to come and fix. God knows how many tens of thousands of gallons they lost, but it put our little bit into perspective.

[Eater Sundae]

Mains fed combi boilers are fine - in our old house I used to fill the kettle with hot water- cheaper and quicker to boil.

 

From a public health point of view it is important that the mains water cannot be contaminated by water from the tank supply, hence the internals of the tap must be designed such that they do not mix until just before they are dischrged. In particular, the internal valve assemblies must control both supplies but keep them separate.

[Draggletail]

Interesting - I'm still in the habit of running any hot from the mixer by running cold before filling the kettle...

 

Nice to not feel like I have to do it anymore

[alchresearch]

Interesting - I'm still in the habit of running any hot from the mixer by running cold before filling the kettle...

 

Same here, although I filter it before it goes in the kettle too!

[Snook]

Doesn't really what water you use if you boil it, I suppose.

 

If your water comes through a combi boiler then it is coming from the same place as the cold, anyway.

[Nagel]

I presume this all goes back to the days when there was a header tank in the attic that filled the immersion heater. As this contained standing water it wasn't always germ-free and drinking from the hot water supply had some risk.

 

But now that most systems heat the hot water directly from the mains the water from the hot tap is just as germ-free as the water from the cold tap.

[metalman]

Was it more to do with the fact that there was lead piping, and the lead only dissolves out into the hot water, which meant that you shouldn't drink from the hot water tap? Now most piping is copper instead it doesn't matter.

[alchresearch]

I presume this all goes back to the days when there was a header tank in the attic that filled the immersion heater. As this contained standing water it wasn't always germ-free and drinking from the hot water supply had some risk.

 

Usually in the form of a dead rat or pigeon!

[Guest sibon]

Was it more to do with the fact that there was lead piping, and the lead only dissolves out into the hot water, which meant that you shouldn't drink from the hot water tap? Now most piping is copper instead it doesn't matter.

 

It might matter if the hot water sits in an old copper tank for a while. Or if you have any lead/copper joints in your hot pipework.

 

I always use cold for drinking, even though I have a combi boiler. Force of habit I suppose.