I know you're probably intending to only remark on leaky water pipes, but:
The New London School explosion was caused by a leaky pipe. It killed 295 students and teachers, and led to the inclusion of smelly thiol in natural gas, as well as the Texas Engineering Practice Act.
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.
Famously, moist wet areas only grow molds that are safe for humans to live amongst, and absolutely never rotted away wooden structural components of a building.