[Jimbee (OP)]

All recipes for coffee or tea, or descriptions on how to make them, say use cool water from the tap. Why is that? And would it even make a difference?

[chris]

In the case of tea, I'd be surprised, because the way tea "works" is that you need high temperature water to extract the tea compounds from the leaves; the high temperature helps to break down the cell structure and release the flavour and other compounds.

Coffee is a bit different, at least if it's instant,  since all of the relevant entities have already been extracted from the bean and then freeze dried to produce the granules. Hence cold water probably won't make much difference to this. The same is not true for fresh coffee produced from grounds though, because that will require heat and pressure to liberate the compounds from the ground beans.

[alancalverd]

I get the distinct impression that Jimbee hails from North America, where the procedures for extracting tea or "tea" with lukewarm water are generally abominable.

The old UK government instruction was to start with "freshly drawn water from the cold (mains) tap" rather than possibly stale and stinky water from a static tank that feeds the hot tap. Though a hot tap was a rarity in most homes in 1939. The starting temperature is not relevant, the biological and mineral content is.

Apropos which, there is one notable exception. British army tanks have a hot water tap at the back for the express purpose of making tea!

[Jimbee (OP)]

I get the distinct impression that Jimbee hails from North America, where the procedures for extracting tea or "tea" with lukewarm water are generally abominable.

The old UK government instruction was to start with "freshly drawn water from the cold (mains) tap" rather than possibly stale and stinky water from a static tank that feeds the hot tap. Though a hot tap was a rarity in most homes in 1939. The starting temperature is not relevant, the biological and mineral content is.

Apropos which, there is one notable exception. British army tanks have a hot water tap at the back for the express purpose of making tea!

Um, I meant START with cold water, before you boil it. I didn't mean MAKE the tea/coffee with cold water. (That would take too long.)

[neilep]

As a firm believer in empirical study I asked a vending machine. All it did was deliver me coffee coloured brown water. So, no luck there !!

[neilep]

I get the distinct impression that Jimbee hails from North America, where the procedures for extracting tea or "tea" with lukewarm water are generally abominable.

The old UK government instruction was to start with "freshly drawn water from the cold (mains) tap" rather than possibly stale and stinky water from a static tank that feeds the hot tap. Though a hot tap was a rarity in most homes in 1939. The starting temperature is not relevant, the biological and mineral content is.

Apropos which, there is one notable exception. British army tanks have a hot water tap at the back for the express purpose of making tea!

Um, I meant START with cold water, before you boil it. I didn't mean MAKE the tea/coffee with cold water. (That would take too long.)

Do you mean...start with cold water that you then boil ?  If so, it may be because most water from the HOT tap is not generally considered fit for drinking.

[Jimbee (OP)]

I get the distinct impression that Jimbee hails from North America, where the procedures for extracting tea or "tea" with lukewarm water are generally abominable.

The old UK government instruction was to start with "freshly drawn water from the cold (mains) tap" rather than possibly stale and stinky water from a static tank that feeds the hot tap. Though a hot tap was a rarity in most homes in 1939. The starting temperature is not relevant, the biological and mineral content is.

Apropos which, there is one notable exception. British army tanks have a hot water tap at the back for the express purpose of making tea!

Um, I meant START with cold water, before you boil it. I didn't mean MAKE the tea/coffee with cold water. (That would take too long.)

Do you mean...start with cold water that you then boil ?  If so, it may be because most water from the HOT tap is not generally considered fit for drinking.

Yes.

There's nothing wrong with hot water from the tap. "Not generally considered"? Well, there's nothing wrong with it. Sometimes it has bubbles in it from the water heater. And it is hotter, so it might have more things dissolved in it that are already in the pipes. But its flowing thru the same pipes in your house that all the other water if flowing thru. So there should be nothing different about it, at least safety wise.

[alancalverd]

There's a great deal of difference, unless your heater is a flash boiler.

Most domestic heating systems in the UK, and increasingly the case as folk adopt heat pumps, use a 200 liter insulated accumulator tank heated by a transfer coil or electric element. So the water you pour into your bath may have been stagnant for months and in many areas will have been treated by a water softener and thus taste salty. Not a problem for bathing or even washing-up, but not warranted as fit for drinking and certainly not a good feedstock for tea.

[paul cotter]

I agree with Alan. The cold water(kitchen) in my house is the only fresh water, all other water comes from an open storage tank in the attic. In one of my employments a dead pigeon was found floating in the attic storage tank.

[alancalverd]

Sometimes it has bubbles in it from the water heater.

Bubbles of what? Time for a new heater, or at least a dose of biocide in the hot tank.

[Jimbee (OP)]

Sometimes it has bubbles in it from the water heater.

Bubbles of what? Time for a new heater, or at least a dose of biocide in the hot tank.

what causes bubbles in hot water?

Google AI Overview

Bubbles in hot water are primarily caused by dissolved air coming out of solution as the water heats up, which happens because hot water can hold less dissolved air than cold water, causing air bubbles to form and rise to the surface; this phenomenon is also related to increased vapor pressure at higher temperatures, making it more likely for air to escape as bubbles.

[Bored chemist]

I agree with Alan. The cold water(kitchen) in my house is the only fresh water, all other water comes from an open storage tank in the attic. In one of my employments a dead pigeon was found floating in the attic storage tank.

Why is it always a pigeon in this story?
 There are more robins,

[paul cotter]

The story BC? I have not heard of a similar experience. I have however found both dead and alive pigeons in house spaces where they got trapped and never any other species- they seem to have an unhealthy attraction to our buildings.

[Bored chemist]

https://www.waterchemist.co.uk/dead-pigeons-in-water-tank/
https://www.reddit.com/r/FawltyTowers/comments/1f5zf6z/two_dead_pigeons_in_tank_take_out/?rdt=52896

[alancalverd]

I'm beginning to wonder if there is some inevitability here. Birds will seek water but not all birds are adapted to float (you need greasy feathers), and even those that can, would find it difficult to fly out of a typical domestic water tank as there isn't enough TODA  to reach Vx and OCH if the tank isn't completely full (it never is). 

So by elimination we are looking for a short-legged non-aquatic bird. Most common bird species prefer to nest and roost outdoors or in shallow burrows but pigeons and chickens do have a proclivity for inhabiting buildings. And chickens can't usually fly into a roof space.

Ergo if there is a dead bird in your tank, it is most likely to be a pigeon, and if a pigeon flies into your water tank, it is quite likely to die there.