Value certainly isn't something you can objetively tie to a fixed number. But water is a good example. It definitely has a value and this value nicely shows the basic mechanisms of economy. First of all, water supply differs strongly by region. Lots of water around the great lakes, little in Arizona. Ocean water is plentifull, but of little value due to the salt, which can be removed only very expensively. So the value of water depends on the distance from the next large water source. This is the reason, Arizona isn't the largest farm state - there is enough sun, but not enough cheap water.

Water for washing your car or watering your garden is relatively cheap, drinking water is not. Because for drinking water you need to get a cleaner source or spending effort to clean it. In many regions, tap water is perfect drinking water (and usually relatively expensive) in other regions not. Bottled water is yet more expensive because of the effort of bottling and transporting the bottled water. Of course you have effects like expensive French bottled water in the US, but that nonwithstanding bottled water is more expensive than tap water which is more expensive than river water.