RE: The Accident

It must have, if you hadn't been there FIL would have had the mess [or he would have delegated MIL]
Things with the white throne will concern you for the rest of your life, for good and bad.
Ignore the job, it washes off, you are none the worse.
Years ago we had an overseas visiting aeroplane arrive at Ohakea, the toilet draining system was "to connect the outlet to a couple of 44 gal drums, open the valve and let gravity do the work".
Normally, everything went well, this time, they had been flying at great altitude where the outside temperature was minus 15 to 20 degrees C.
Everything was frozen, they did the connection, valve bit, nothing happened.
A brave soul was given the task of chipping through the blockage with a screwdriver until he reached paydirt, then quickly [very quickly] refit the connection.
He didn't do too bad, just a shower and a clean pair of overalls required.
The driver was still laughing as he drove off, turned the corner past the bosses office too quick and rolled the trailer, complete with contents across the road.
It took the fire brigade and their trucks an hour or two to clean up the mess.