Tap Water Quality: Comparing Cold vs Warm Water Parameters, Bacteria, Nitrates & Taste

Question

More than once I have heard that supposedly water in the tap, depending on whether it is cold or warm, has different parameters. Apparently, hot water is not as purified as cold water and it can cause more bacteria, etc. I would like to dispel myths and my doubts. While searching internet forums...

Tommy82 · Answer

When it is heated, the ability of the water to dissolve things changes.
Therefore, for example, limescale builds up in the kettle. Well, no matter where the water from the kettle settles, it won't have it either.
There is also something like Legionella and hot water strings are to be able to temporarily raise the temperature just for disinfection purposes.

Artur k. · Answer

As far as I know, hot water is nothing but heated cold water. Hot water comes from the heat and power plant (often above 100 degrees Celsius), in the heat exchanger it heats the cold water from the network and goes to the taps.
Hot tap water should have the same properties as cold water heated in any way (e.g. with a kettle) to the same temperature.
A heat exchanger is like a transformer - it has a primary circuit and a secondary circuit (as in the winding transformer), the circuits are not in direct contact with each other. Hot water from the network is actually dirty and as such is only suitable for central heating (it is used for this purpose). Nothing to do with drinking water.

Stefan_2000 · Answer

Well, not always. After years, heat exchangers may start to leak, if they leak outside, sooner or later someone will notice it, but if there is a leak inside, people will get an addition of industrial water to the hot water, because water in the network has a higher pressure. Apparently, during the People's Republic of Poland, technical water (overheated steam?) From the mains was colored (or some fragrances were added, I don't know) just to detect leaks in exchangers. Therefore, it is a very silly idea to take hot tap water for making tea :-) kisses, St.

Artur k. · Answer

Yes and no. In the past, it could have been so, now in practically every heat node there are appropriate electronic systems that control the temperature and pressure of both circuits as well as the temperature and pressure of the returns (the return is colder). If something is wrong - they turn it off, it works a bit like an electric RCD. On the basis of this data, the controller is able to show how much energy the building consumes on its display.
I don't know much about it, so I won't go into the details. I know what my uncle, who has been dealing with this for 30 years, told me.

lynx22 · Answer

As Artur near. Warm water is warmed up cold. The differences in parameters result from the fact of changes taking place under the influence of temperature (e.g. decomposition of bicarbonates, which in turn leads to the precipitation of carbonates). In addition, cold water with the tap turned off stands in the pipes, and hot water circulates in a closed circuit all the time, which ultimately results in many heating and cooling cycles.

jankolo · Answer

Let me make the following quote: On the Bergamut Islands Apparently there is a puss in boots, The donkey was also seen, Whose ant was carrying, There is a playwright Laying golden eggs Apples grow on the oaks In ermine caps, There is also an old whale, What wears glasses Moons are learned In tomato sauce And trained rats On top of a glass mountain There is an elephant with two trumpets And only ... these islands do not exist. Whether hot steam is circulating in the network or superheated steam does not really matter, after all, both substances are the same H2O. In the People's Republic of Poland, everything was possible, even coloring and giving the smell of overheated water vapor.

Janusz · Answer

What my colleagues write out is pure theory.
In practice, the hot water that flows from the tap is unfortunately more polluted.
In my house, the screens next to the faucets or aerators are often clogged - only those "on the hot side".
Often also after a temporary lack of water - heat is just one muck ...

tronics · Answer

@Janusz - my colleagues clearly indicated that there are temperature dependencies on the solubility of many substances (including chlorine, oxygen, co2, as well as bicarbonates and ferrates) in H2O. For this reason, in many cases domestic hot water pipes and valve filters on the domestic hot water side most often get in the butt - in my case, precisely because of ferrous materials. A dozen or so km away, another water supply plant, a different chemical composition. and the dominance of calcium and magnesium carbonates. In addition, there is the case of legionella, which has already been mentioned: - in cold water pipes it does not have such conditions for development as in boilers and hot utility water pipes.

Artur k. · Answer

Janusz - this muck is just dried rust, it also flies from the cold. There is more flow from the hot one, because you have circulation and the water has to travel twice as long - so it will collect twice as much muck from the pipes. Circulation is needed for the residents of the last floors of a multi-story building to have hot water immediately after turning on the tap. If there was no circulation, you would have to wait for the water from the basement heat node to reach the top floor. Not only is it inconvenient for the inhabitants, but also a terrible waste of water.

Chris_W · Answer

For the sake of accuracy - the primary circuit is not regulated in terms of temperature or pressure (it belongs to the heating plant), but only the flow - solenoid valves set such a flow on the primary one to obtain the set parameters (temperature) on the secondary one. The node controller should (and most often has) periodically raising the temperature on the secondary in order to sterilize the installation.

Artur k. · Answer

That's right - the primary circuit temperature is not regulated but monitored. On this basis, the energy consumption is calculated. And on this basis, it is quite easy to find a leak - the usual energy balance.

Mirosław Śmielak · Answer

Colleague Chris_w and Artur k. - take care of your statements about electronics, because maybe you are more oriented there. Who has heard of the periodic increase in water temperature for sterilization? valves of the Samson type (older installations) or electronically controlled, which self-regulate and maintain the set temperature.
steel) and corrosion, as well as economic and safety factors
The boiler scale and water contamination (stagnation in rarely used sections of the installation) cause water contamination.
monitoring? if there is a leak, you can see it. Penetration of so-called SPEC water
it was possible in the old type of "Jad" exchangers, but these are no longer used
in residential buildings, and that was it.

tronics · Answer

Well, here is a quote from Wikipedia, thank you friend for such an interesting and valuable comment.

lynx22 · Answer

The last two statements are not exclusive. Installations are adapted to increase the temperature in the circulation, but rather it is not done periodically, only when the presence of bacteria is detected.
My expensive Wikipedia is not a reliable source of information for me, but only an indication of where and what to look for.

bonanza · Answer

Rather periodically.

Krzysztof Kamienski · Answer

Mirosław Śmielak_ Yeah, everything is clear, but you forgot to add that each heat exchanger, not only the famous JAD, can have an internal leak, and a lot of interesting chemicals are added to the primary circuit (flowing through the boiler piping) to soften this water to protect the installation from precipitation scale, and corrosion inhibitors.
Bon Appetit

Artur k. · Answer

Although the CW temperature is indeed set to 55 degrees. Only if someone questioned it, Mr. Buddy Mirosław Śmielak ?

Mirosław Śmielak · Answer

Answering K. Kamieński, I explain that the currently produced plate heat exchangers are made of acid-resistant steel and the leaks we are talking about do not occur (they do not corrode like the old JADS). accumulated sediment, but then you have to turn off such an installation. Inhibitors are used in installations which are also recommended there.

Tap Water Quality: Comparing Cold vs Warm Water Parameters, Bacteria, Nitrates & Taste

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