Water distributed through the network of pipes in any city has to be artificially pressurized, often using compressed air, to keep it moving through narrow pipes for long distances, according to Huffington Post writer Steven Hoffer, who had the clearest explanation of anyone at the time.
When it's piped into a building that pressure has to be reduced using a series of valves or pumps. If the pressure-relief valves malfunction, the results can be unpleasant.
Under pressure, the flush valve on a toilet opens a pressure-relieving portal, reversing the direction most of us prefer a flush to work.
At worst, under any but the absolute worst-case scenarios, someone could get messy and wet, according to Huffington Post's experts.
At GSA, someone apparently turned on the manual control for the pumps that make sure water has enough pressure to make it up to all eight floors of the office building, which is on the corner of 7 th and D streets.
Leaving the pumps on let the pressure build until many pipes were filled with air under considerable pressure, pressure that caused at least two toilets to burst when they were flushed.
"At approximately 12:30 PM on 9/26/11 I was notified that there was an emergency in the 4071 Restroom and that someone had been injured," Supervisory Property Manager Chris Litsey wrote. "Upon arriving we found Nurse on site administering aid to the injured employee…it was apparent that the injury was caused by the fragment of a broken toilet bowl.
The upper portion of the bowl, where the water supply comes out was broken and the trap on the bottom was also broken. People on site told us the toiled 'exploded.'
We found that the waterlines to toilets in that restroom were dry and flushing the toilets created a loud and startling sound and also ejected the remaining water from the bowl.
…An air compressor was running, creating pressure in the domestic-water tank and may have contributed to this incident. This compressor was immediately turned off, pressure valves were opened to reduce the pressure in the tank and the tank was allowed to fill with water." Supervisory Property Manager Chris Litsey, incident report 8:44 a.m. Sept. 27, 2011.