Naked Science Forum
Non Life Sciences => Chemistry => Topic started by: thedoc on 17/01/2014 16:30:02
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Tad asked the Naked Scientists:
In its basic form, as even some ten-year-olds could tell us, water is just H2O - two Hydrogen atoms, and one Oxygen atom, but that's not necessarily what we humans get from our tap.
So my question is straightforward (although I doubt if the answer will be), what else does ordinary tap water contain besides H2O, and what effect might those things have on human behaviour and human health?
Regards
Tad
What do you think?
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It would depend on where you are. City water vs well water.
Your water typically has some dissolved minerals, which can give a distinct taste to the water depending on the source, and can lead to the buildup of scale in the bottom of a hot water heater or electric teapot.
The majority of minerals are not harmful to the health, and may even be beneficial, although a few metals such as arsenic are bad, and should be tested for.
City water is usually treated with chlorine to kill off microorganisms without harming people. There have been studies about the protective impact of naturally occurring fluorine in the water and healthy teeth, so some communities also add fluorine to their municipal water. Chlorinated water is harmful to fish, but can be set out to allow the chlorine to evaporate before filling a fish tank.
There may be some bacteria in untreated water. In a well designed system, the sewer systems and the drinking water will be adequately isolated, and there won't be pathogens in the water. Filters can also help.
That may not be the case around the world. In Egypt they recommend not to drink the water. I sampled some... and will say that it is best NOT to drink the water.
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Methane ... [:0]
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Interestingly, in blind tasting tests, New York tap water scores consistently higher than any bottled water, and in "open label" tests, the more expensive or full of ecobullshit or pseudoscience the label, the higher it scores even if all the bottles are filled with identical tapwater.
There has been a deterioration in UK tapwater quality since privatisation. Oldfashioned municipally-owned water was of good industrial quality, sometimes a little overchlorinated (though some plants used tasteless ozone) but containing no live organic matter. Thanks to the European Union rules on competition and water quality, it now has only to be potable, so most of it contains brown algae that are not harmful to human health but clog up machinery and cause untold economic damage (except to the water companies, of course).
Aside from organics, tapwater contains traces of various common inorganic materials, mostly calcium or magnesium salts. These are harmless but tend to form scum when mixed with soap as the stearates and palmitates are insoluble, or deposit as carbonate residues (lime scale) as the bicarbonates decompose when the water is heated.
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There has been a deterioration in UK tapwater quality since privatisation. Oldfashioned municipally-owned water was of good industrial quality, sometimes a little overchlorinated (though some plants used tasteless ozone) but containing no live organic matter. Thanks to the European Union rules on competition and water quality, it now has only to be potable, so most of it contains brown algae that are not harmful to human health but clog up machinery and cause untold economic damage (except to the water companies, of course).
The UK is dealing with an aging municipal water system in which as much as a quarter of the water leaks out (http://www.bbc.co.uk/news/uk-17622837).
It is my belief that any company that is granted a monopoly by law should be a public corporation. Apparently the local electric company was founded in 1908 due to a typhoid epidemic with with the previous private municipal water company (http://www.eweb.org/timeline).
Algae is a bit of a pain, but not particularly harmful. Chlorine, and keeping the pipes sealed and dark should help, and it should be easy enough to filter out.
Iron and galvanized pipes, of course, can taint the color of the water.
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While H2O is the basic formula for water, water often forms temporary aggregates of two or more water molecules, eg H4O2. A charged ion in the water (eg Na+) is often surrounded by a cluster of 10 or more water molecules.
Some new plastic pipes in our house left the water with a distinct taste. Running the water for a few seconds before filling a cup resolved that problem.
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Some new plastic pipes in our house left the water with a distinct taste. Running the water for a few seconds before filling a cup resolved that problem.
That's also the strategy if you have lead pipes in your home ...
If you have a high lead content in your water it is recommended by the Drinking Water Inspectorate that you should:
refrain from drinking water that has been left standing in the pipes for more than a few hours. Draw off a washing-up bowl full of water to clear out the water (if your lead pipework is longer than 40 metres you will have to draw off more water);
http://www.ciphe.org.uk/professional/public-health/lead-poisoning/
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Tapwater contains many salts like that of Mg Ca Etc