system
Given the following post, respond as if you're commenting on Reddit:
human
Why isn't water used in hydraulic applications like vehicles?

If water is generally non-compressible, why is it not used in more hydraulic applications like cars?

Could you empty the brake lines in your car and fill it with water and have them still work?

The only thing I can think of is that water freezes easily and that could mess with a system as soon as the temperature drops, but if you were in a place that were always temperate, would they be interchangeable?

Obviously this is not done for probably a lot of good reasons, but I'm curious.
gpt
1. Water is not a lubricant.  
2. Water Rusts metal.
3. Water has a high freezing temperature and a low boiling point
3. Water has a ton of impurities.  Some systems that use water must use RO/Deionized water.  This would be very dangerous in the field.
4. Water will be quickly contaminated by the environment as it is a solvent.
6. Water cannot sustain much vacuume before boiling.  

This is why water is almost never used as a hydraulic fluid in machinery.