WaPo:

After a toilet exploded at a General Services Administration building, sending a female employee to the hospital with serious injuries, the bathrooms were declared off limits.

After the explosion, an internal memo was issued:

“DO NOT flush toilets or use any domestic water... Due to a mechanical failure, there is high air pressure in the domestic water system that resulted in damage to toilets.”
What do I fear more than an exploding toilet? A rat in the toilet bowl.