This is an interesting question. There is indeed water on Mars, but it is not necessarily bad for us! In fact, because there is water on Mars, it may be an indication that people could live there one day! This does not mean, however, that we would want to drink the water that is currently there as it is. Most of the water on Mars currently exists as ice, or as briny solutions in some parts of the soil. We would not want to drink briny water in the soil on Earth, so we would not want to drink such water elsewhere either.

To answer the second part of your question: as far as we know, there is no life on Mars. It is thought that finding water on other planets or moons may be a first step to finding extraterrestrial life, since it is necessary to all the kinds of living organisms we have encountered so far. However, we are interested in space exploration not just to find other life, but to understand how the universe came to be and what else is out there. I hope this helps!