See the Wisdom section for more instructions, hints and tips.
Water is necessary for all life, the only thing we need more of is oxygen and it's normally available in the air around us. Water is a bit more difficult to come by. And since it is very precious to our bodies, they are designed to conserve it.
You can only survive at most a few days without water. You can survive several weeks without food.
We take water almost for granted because running sanitary water is everywhere.
Backpackers are more aware of water because they must carry their supply with them. They have to locate water sources like a pond or stream to replenish their supply.
In the time of Jesus, water was a much more precious resource. Jesus lived in an arid climate. He didn't have a canteen, there weren't any faucets. They had to walk to a well, river, or lake and carry water back to their house. Remember that water weighs over eight pounds per gallon. A person needs several gallons of water every day for drinking, cooking, and washing. That's a lot of weight to carry.
Water was likely on their minds frequently. Like the Samaritan woman at the well (John 4:5-42). At first, she wanted the "living water" so she wouldn't have to fetch water daily. Then she understood that Jesus was speaking about the spiritual meaning of living water.
It's no wonder that Jesus used water so often in this parables and teachings.