Can't imagine how this would happen but I have basement toilet (feeds to a grinder pump) that has started draining slowly and most of the time does not completely flush on the first time. There is a bar sink and dishwasher feeding the same pump and neither have drainage problems. The water level rises and (by my interpretation) seems to drain slowly - not sure how that is regulated. Tried plunging numerous times but it does not help or make better. Any suggestions?