* Water is always a liquid. This is false because water can exist as a solid (ice), a liquid (water), and a gas (water vapor).
* Water is a good conductor of electricity. This is false, pure water is actually a very poor conductor of electricity. It's the presence of impurities like dissolved salts that make water conductive.
* Boiling water kills all bacteria. While boiling water kills most bacteria, some highly resistant bacteria (like spores) can survive.
* Drinking more water can flush out toxins from your body. This is a common misconception. Your kidneys and liver are responsible for filtering toxins, and drinking more water won't make them work any better.
Let me know if you'd like more examples!