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!

No one knows if there is presently life on Mars or if there was life in the past there that has become extinct. What we do know is that IF there is life, it is microbial. That is there are no plants or animals. Basically, we will not really know until we go there or study it with very sophisticated robots.

There is no proof that life exists on Mars but there is evidence that may suggest there is or was life on Mars.

A meteorite was found in Antarctica that came from Mars and some of the chemicals and fossilized patterns found on the meteorite could possibly have originated from a living organism that was similar to bacteria. However, there is much controversy on whether or not the chemicals and fossilized patterns actually originated from Mars or are contaminants from the environment in Antarctica.

More recently scientists have discovered that the gas methane exists in the Mars atmosphere which suggests that either a volcano had recently erupted causing the methane gas or a life-form similar to some bacteria on Earth is metabolizing carbon dioxide and hydrogen, producing the methane gas. Other gases and chemicals in the Mars atmosphere are metabolic waste-products of certain life-forms on Earth, suggesting that life may have caused these chemicals to exist on Mars.

I think there is a pretty good chance of life having existed on Mars and maybe still existing today. But I think that any life forms on Mars will be very primitive, similar to bacteria and microbial life on Earth.