I was dumping bacon grease down the drain for 8 years until a plumber quoted me $1,200
He pulled out a grease blob the size of a softball and asked if I cooked bacon a lot. Now I keep a $2 coffee can on the stove and pour it in there, then use the fat for frying eggs the next morning.
Did you know a friend of mine went through the same thing last year? His wife dumped grease down the sink for years and one day the whole thing backed up while they had people over for dinner. Now they keep an old soup can by the stove and it costs them nothing, which beats a plumber bill any day.