Even leaky water pipes kill people - just google Legionnaires disease.

A drip or stream from a leaky pipe isn't gonna do it. You need to get the bacteria into the respiratory tract to get legionaires disease. And even then a specific temperature water is necessary for it to grow.

A dehumidifier (or an HVAC system, which is where the name of the disease came from) is more likely to give you legionnaires disease than even the most substandard plumbing.