i don't know, use your head dum dum!
Although at least two thirds of our planet is covered with water, less than 2% of it is drinkable. However, salt water can be made drinkable through desalinization and other filtering or processing.
No. The earth is 70% water, and less than 1% of that is drinkable. The earth doesn't "Make" water as fast as we need it, and we can't purify the seas.
Fresh water typically has a saline content of less than 0.5 parts per thousand, brackish water 0.5-30, and saltwater 30-50
0.03%
There's no problem making sea water fit to drink, but there is a problem doing it cheaply enough. If there is freshwater around, it's usually less expensive to process that into drinkable water.
Ocean survival kits once used a chemical that would bind to the salt and sink to the bottom of a container. The less-salty water at the top of the container would be drinkable. Life rafts today may carry "reverse osmosis pumps" that force seawater through a permeable membrane to separate out the salt.
It goes in as a vapor and comes out as a liquid.
The total amount of water on Earth has remained relatively constant over the past 100 years. However, changes in the distribution of water due to activities like urbanization and climate change may have altered the availability of freshwater in some regions.
Water is even more important than food in a survival situation. Clean, drinkable water can keep you alive for weeks, whereas without water you will perish within a few days (or less, in a harsh, dry, hot climate).
Quite a bit less then today.
71% of the world is covered with water, but the oceans are so deep, 97% of the water on Earth is salt water. Of the remaining 3%, about 2% is in glaciers or otherwise unattainable. About 1% of Earth's water is drinkable quality found mostly in fresh ground water.
Almost all, if not all natural water is at least marginally polluted by natural and artificial sources. Pure water is almost always man made. A tougher question would ask what percent is drinkable or suitable for habitat.