73

Reboiling water will do precisely three things: Some volatile contaminants in the water that survived the first boiling might be driven out by the second boiling. Some additional evaporation will occur, causing anything dissolved in the water (salts, contaminants) to be slightly more concentrated. Some additional material from the surface of the vessel you'...


45

First of all, it depends on how the tap water was treated before it was piped to your house. In most cases, the water was chlorinated to remove microorganisms. By the time the water arrives at your house, there is very little (if any) chlorine left in the water. When you fill you container, there is likely to be some microorganisms present (either in the ...


37

I cannot think of anything in tap water that would make the water undrinkable after a couple of days already. Tagging the question with biochemistry probably points in the right direction. The only effect I can think about is growth of anaerobic microbes, e.g. Escherichia coli, causing diarrhea. There's good chance to keep the water from 'going bad' and ...


29

I am glad you asked this question. There is an element of truth here. If the water already contains contaminants such as arsenic and nitrates, and/or if the pot that the water is being heated in is contaminated, then boiling (or equally well, reboiling) the water could result in higher levels of these contaminants. On the other hand, if you are starting ...


25

EZ-water is not a breakthrough. It is not new, nor is it valid. This appears to be one of the many claims about the healthful benefits of drinking "ionized water". The original "article" linked, contains a number of misleading . Water molecules make up 99% of your body. This is true, but misleading. According to various sources, the human body is between ...


23

There has been some claims that drinking reboiling water is dangerous claiming it produced arsenic, nitrates etc. it this true? It doesn't produce anything. Re-boiling water doesn't change the water into anything dangerous. However, if the water is already contaminated, then lengthy boiling will evaporate some of the water, and the concentration of the ...


18

There is a very unusual case in which reboiling water makes water (marginally) more dangerous to drink. Suppose that you have a toxin or pathogen in the water that is neither volatilized nor denatured at 100 degrees Celsius. By boiling the fluid, you reduce the amount of $\ce{H2O}$, while the amount of the dangerous substance remains constant. Then, a ...


13

Yes, this is possible and is a process called reverse osmosis. It is based on a membrane which lets water pass but not the salt ions (and other water contaminants). From Wikipedia: The membranes used for reverse osmosis have a dense layer in the polymer matrix -- either the skin of an asymmetric membrane or an interfacially polymerized layer within a thin-...


12

A few lazy weeks of summer cottages, camping far from the beaten track or boat excursions in the archipelago: When summer comes, we seek to be closer to nature. Sometimes that means we may waive some of everyday life's certainties, like drinking water straight from the tap. Do this! Fill the drinking water of good quality, such as municipal drinking water ...


12

The tap water is likely "hard," i.e., contains some dissolved mineral salts, most likely (primarily) calcium and magnesium carbonates and bicarbonates. The anions of these salts are slightly basic, consuming $\ce{H^+}$ ions and thereby raising the pH. Carbonates (with the obvious exception of alkali metal salts) are only sparingly soluble in water, while ...


7

Unfortunately there are no (or only very hard to find) studies to the mechanism of the actual sorption of arsenic (acids) to magnetite. Most literature does describe it as a simple Ligand exchange, although I find that hard to believe. From what I have read[1-4] I will try to compose some hints on what may happen. First of all lets have a look at arsenic ...


6

I am not an expert and its been a long time since I last studied chem and bio. The best answer will probably only come from a biologist. But out of interest, I will try to answer. Also, I suggest that you post this question on websites such as http://www.askabiologist.org.uk/ . Its likely that you will get some good answers there as well. Assuming that the ...


6

Aquatabs can certainly be used as a disinfectant in a small swimming pool like you've described. The active ingredient has many uses, including drinking water treatment as you've pointed out, but it is also used as a disinfectant in swimming pools. According to this Wikipedia article regarding the active ingredient of Aquatabs, sodium dichloroisocyanurate:...


5

There are many filters which do not remove fluoride from potable water. Boiling or freezing does not help either. Reverse osmosis filtration may be a solution. However they are expensive ($100+). Activated alumina defluoridation filters are used in areas where contamination from fluoride is common. These can reduce fluoride levels from 0.5 ppm to 0.1 ppm, ...


5

It depends on the water. If the water is already contaminated, then after a couple of days, there are more chances of water to go bad. But if the water is mineral, already purified, then it takes too many days. Also the other fact about the sunlight, if the water is directly faced with sunlight, then sunlight causes formation of the algae in water. In ...


5

This is just a very short explanatory note on the article suggested by Greg E.. The reaction between ascorbic acid and hypochlorous acid is as follows: $$ \ce{C5H5O5CH2OH + HOCl → C5H3O5CH2OH + HCl + H2O}$$ so for 1 mole of hypochlorous acid you need 1 mole of ascorbic acid. This can be recalculated into a mass ratio by the use of their molecular masses: $$...


5

Yes , a quick and cheap way to reduce chlorine residual is to add ascorbic acid (VITAMIN C), which if added in an equal molar amount to free chlorine would completely eliminate chlorine residual within 1 min. I am quoting from ABSTRACT from a paper from, Int. Journal of Engineering Research and Applications , ISSN : 2248-9622, Vol. 3, Issue 5, Sep-Oct ...


5

Ozone is a powerful oxidizer (redox potential of 2.07) and will kill bacteria and destroy viruses (not sure if I can say it kills viruses) by transferring oxygen atoms to them. It also decomposes in water forming OH radicals, which quickly oxidize organic and inorganic compounds. Ozone can also react by ozonolysis, breaking compounds which have double or ...


5

Boiling a water mixture doesn't always produce pure water. Boiling a solution of salt and water (or evaporating the water) will separate the salt from the water, but those are compounds with very different properties. In the making of distilled alcohols (Ethanol), the vapor phase has more alcohol than water. Repeated distillations can increase the ...


4

Toilet bowls are made of ceramics which can contain feldspar. Toilet bowls also often have a feldspar glaze. There is a study that disolved Cr(VI) can be removed by feldspar. Studies on the removal of Cr(VI) from waste-water by feldspar http://onlinelibrary.wiley.com/doi/10.1002/jctb.280530204/abstract The IMA currently recognizes 90 Cr bearing minerals. ...


4

As mentioned in the comments, water is often treated by ozonation in order to sterilize it and ensure it can be drank with no ill effects. Ozone is a very reactive gaseous allotrope of oxygen, produced in situ by exposure of atmospheric oxygen to UV-B light (in fact this happens naturally in the stratosphere, generating a thin ozone blanket covering the ...


4

Water treatment plants typically buffer the pH of the water supply to be slightly alakaline, with a pH of ~7.5-8 normally (the standard is that it must be between 6.5 and 9.5) with various chemicals including Sodium Hydroxide (lye) or Sodium Carbonate (soda ash). Take a look at this photo from Wikipedia which shows all of the chemicals added at this ...


4

Water issues tend to be very specific to a certain location, so it is not possible to say exactly for sure what is happening in your situation. Pure water has no taste. The taste comes from the impurities. Impurities, which are almost always present, can partially be removed by the filter shown. That filter looks like a carbon filter which is effective ...


4

Is it possible that this use of UV radiation may lead to cancer in humans? No! The lamps used for water treatment are usually low pressure mercury vapour lamps. These lamps emit in the UV-C range with a maximum at $\lambda = 254~\mathrm{nm}$. No mercury can escape from an intact lamp. In principle, UV-C radiation may cause severe sun burns and harm your ...


4

Chlorine and Free Chlorine Chlorine is the term commonly used to describe the addition of chlorine gas, sodium hypochlorite (i.e., bleach), or calcium hypochlorite (i.e., bleach powder) to water to form free chlorine. Free Chlorine is the sum of hypochlorous acid ($\ce{HOCl}$) and hypochlorite ($\ce{OCl-}$); a monoprotic acid with a $\ce{pK_a} = 7.54$. ...


3

Test strips for chlorine should work for both chlorine- and chloramine-treated water. See Here-to-learn's comments to this answer for the chemical kinetic reason why chlorine test strips will also work for chloramine-treated water. Notice that your city supplies the water with chloramine. Depending on how much chloramine is present in your tap water, ...


3

It appears your creating calcium aluminate by reacting aluminum with alkaline water. Since that is probably not wanted in the brew, you might use glass or anodized aluminum, which is more resistant to chemical attack, and a water softener, if the calcium carbonate isn't wanted, either.


3

Actually, the salt in seawater doesn't kill you directly. It dehydrates you and you die of thirst. If you mixed 1 part of seawater with 2 parts of fresh water, it would not dehydrate you, but you would need to eliminate the excess salt so you would need to drink a lot of this salty water. There are many living things in seawater that can kill you. Red Tide (...


3

Hard water and soft water differ only in the presence or absence of certain impurities: Hard water: Water with impurities in the form of minerals containing calcium and magnesium added in. Soft water: Water with these minerals removed. One thing to note is that hard water is not the slightest bit dangerous. Studies have been conducted by the World Health ...


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