A tenant called in to report that their toilet overflowed and caused a pool of water on the floor. After cleaning up the mess and since they didn't have a plunger, they went to the store to purchase one. The tenant could hear no water running in the tank and thought it was safe to leave the issue to be resolved once they returned. When they returned there was water dripping from the dining room ceiling. Apparently while they were gone some two hours, the water to the toilet continued to run and overflow causing a "Black Water" flood. Black Water is a term for human sewage and anything that Black Water touches has to be replaced. The water not only was coming through the dining room ceiling but had also flowed into the master bedroom and the closet. The remediation company had to cut out all the contaminated carpet, flooring, and the majority of the dining room and kitchen ceiling. It was determined that the toilets flow valve was not turning off completely and was allowing just enough water to rise in the tank and go into the overflow tube. This easy fix became a $13,000 insurance claim. This issue can be detected when there is a slight ripple on the edge of the water in the bowl. This is something we check for during every quarterly inspection!