We can never run out of water as the amount of water on our planet is constant from the age of the dinosaurs to the present. If water gets polluted we can always purify it. Also, if freshwater becomes saltwater due to various reasons we can always remove the salt and make it freshwater again, can't we?Then why are water resources still regarded as limited?

Note : I asked the same question previously but was not able to arrive a logical conclusion for my question so I asked the same question with some modifications.

Yes you are right with the fact that as our earth is composed 3/4th of water, we have huge amount of it. But only 3% of it fresh water and 2% is frozen in the form of glaciers. Less that 1% of the total water is fresh water which is available for human use. Sometimes, pollutants cannot be separated successfully and extracting pollutants out of them becomes very expensive. Converting salt water into fresh water is also very expensive. So, it is best to conserve water and use it judiciously. Wastage of any kind should be avoided as it is not a good habit.