Chemistry - Does water really 'go bad' after a couple of days?
Solution 1:
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 container or in the water). In a nutrient rich environment, you can see colonies within 3 days. For tap water, it will probably take 2 to 3 weeks. But that doesn't mean that the small amount of growth doesn't produce bad tasting compounds (acetic acid, urea, etc.).
BTW Nicolau Saker Neto, cold water dissolves more gas than hot water. Watch when you heat water on your stove. Before it boils, you will see gas bubbles that form on the bottom and go to the surface (dissolved gases) and bubbles that disappear while rising to the surface (water vapor).
Solution 2:
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 even 'turn it good' again when keeping the water in PET bottles in the sunlight, letting SODIS (solar disinfection) work for you.
Solution 3:
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 in sterilized bottles or cans. Keep the water dark and as cool as possible. That keeps drinking water fresh for at least one week.
Smell and Taste
- Putting a limit on how long drinking water can be stored has more flavoring to it than health risks, says Torbjörn Lindberg, State inspector at NFA.
- The risk of getting sick of water is small in Sweden. But you should of course do not drink water that tastes or smells bad, is turbid or highly colored.
Get microorganisms in drinking water
Good drinking water does not contain pathogenic microorganisms, such as viruses and bacteria. It is also a nutrient-poor environment that makes it difficult for such microorganisms to survive. They are simply ill-suited to the aquatic environment. If they are there from the beginning, it is therefore likely that they will disappear over time, and the risk of getting sick is reduced.
Drinking water can be bad
Sometimes, bacteria, micro-sponges and algae that are adapted to the aquatic environment are found in the drinking water from the start. They can also multiply over time. It is completely natural and gives no health risks. However, drinking water can start to smell or taste badly, especially if kept long and hot, for instance in the sun. It can also be colored and can form a slimy layer on the inside of the container.
Solution 4:
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 water in the bottle is thoroughly "purified" at the water plant , there has been absolutely no contamination (pipes, faucet etc.) on the way, and the bottle and handler are clean, then it is unlikely that water will go bad. Example that suggests contamination at faucet - http://www.journalofhospitalinfection.com/article/S0195-6701(98)90295-X/abstract
I don't think that most bottles are 100% air-tight. So, the next thing I would check is if there are any water-borne pathogens that can spread by air. If such pathogens exist, then is it possible for them to enter the bottle through small "air spaces" ? That seems unlikely to me.
So, if water is microbe free and can be kept that way by a bottle, then it should be good for a "long" time.
Solution 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 simple words, you can drink a water, if it is a mineral water, then after couple of days, if it is a tap water, 2-3 days normally.
This is my individual opinion, I am not a doctor. You follow what you want. :)