There are many sources for water. Wether it comes from a well, septic, rivers, springs, and other bodies of water. I believe water can only go bad in cause of cross-contamination. There is no expiration date
However, in certain countries/third world countries, the tap water may not be safe to drink. In some places, tap water is pretty hazardous to your health, the water can be boiled, or there may be a place you can go pump your own, "clean" water...
Example: in Seoul, Korea, the water is unsafe to drink. It is okay if boiled, but in most cases, we would walk to pump our own water from the well.
In the USA, the government has tried to fortify water with sodium fluoride. Which has been done throughout Washington DC. Sodium Fluoride is used in dentistry to help harden teeth, keeping them healthy. In reality, there is no proof that this is actually healthy and in fact, a high dose of Sodium Fluoride can be harmful to children. With that being in some water, it can be "bad" if consumed in large quantities.
The best water I find is Natural Spring Water... Filtered It's clear, crisp, and refreshing. Also, there are no additives (that may give a nasty after taste) And is safe and healthy for all ages