The drain sock was invented by a pipe-fitter in Tampa, Florida, after he and his men had some water damage on a project. After the damage was paid for by the insurance company it was found that modifications had been made to the system with no revisions made to the "As-Builts". Although this was no fault of his own and he was hearing some of the same stores from many other fitters, he couldn't help but feel that there had to better way.
He couldn't accept that in a field that could make a sprinkler head spray 20' or more, smart heat detectors and valves that can do anything, the only way to pull a sprinkler head was to hold a 5-gallon bucket under it.
When there is more than 5-gallons of water in the pipe the fitter is left putting his finger in the hole while his helper carried an open bucket of stagnate water to the drain.