I tried the plunger, hot water and even heavy duty drain cleaner. The sink and shower drain in our bathroom still ran too slow. I have been guilty of letting the water run when I brush my teeth. However, I could not do that with our sink because the water drains slower than the tap fills it up. The shower drain had a puddle in the middle as the water was trying to drain. I called a place that does drain cleaning in Bronx NY when I thought about the shower spray churning up water from inside the drain onto my feet.
The toilet also would get stopped up. Sometimes you had to flush two or three times just to get liquids to go all the way down. Solids, if you know what I mean, could be a real problem. It was embarrassing for guests at times. Funny to me, but embarrassing to them. I could here them in there trying to quietly use the plunger. Then the drain would let go and you would hear the glug, glug glug really loud!
The place we called that does drain cleaning in Bronx NY found a hard clog stuck to the inside of the sewer main that lead from the bathroom. Toilet paper and other solids would catch on it and build up. Then it would let go on occasion, but the main hard clog was stuck solid. They used a power snake to clean the pipe clear of that hard clog
The clog looked like Plaster of Paris, and that makes sense. We did a few projects with the kids for school last year that used that plaster. I found out that it hardens by chemical reaction and running it down the drains can cause it to gather and clog a pipe. I thought the water would dilute it and there would not be a problem. The stuff can harden in a sewer pipe without a problem.