I have a slab house about 50 years old. The tub/shower drains slowly and during the bathroom remolding I was able to remove the trap for the tub which was filled with black sludge. I also bought a rubber attachment that you put on a garden hose and it expands inn the pipe forcing water through. I ran this for about 30 minutes and replaced the trap with PVC going to the old cast iron. After installing the new tub I find it drains much better but still slow, about 2 inches of water by the end of a shower remains.

All other fixtures seem to drain fine but I can’t get a snake through bends of the tub drain. I assume the pipe may be corroded or has some type of build up inside. Another observation is the bend in trap exiting to sewer is just below slab level, about 3 inches. Could there not be enough fall or drop in the line to get gravity to help pull water down?

Thank you in advance.

You've described the problem very well. I don't know what a plumber's answer might be though. Once my tub/shower had that problem, nothing seemed to help. Then I dyed my hair, and when I rinsed the color out the slow draining was corrected. Revlon colorsilk, it was something in the chemicals? Drain cleaners hadn't touched the problem.

I have one quick suggestion... The easiest thing to try is the plunger.. believe it or not... the plunger... BUT there is a trick I will tell you about.

Here, you will need to remove the screws from the faceplate of the tub waste and overflow assembly and pull out the spring mechanism or similar that allows the tub to fill or drain... You may find that this is half the problem right there (hair catches on spring in the drain). NOW, carefully put a wetted rag into the overflow pipe (do not stuff down and into, just into the pipe an inch or so... idea is to cut off any back pressure when plunging) and hold down with a screwdriver or similar tool. THEN add about two inches of water into the tub (remove the strainer if in place) and using the plunger, plunge the drain line aggressively... now, even here there is a trick...

Push down gently and then pull back aggressively.. can get a bit messy, but you will be amazed at what comes back up and out the drain.

Then, if that does not do it.. push down aggressively and pull back gently... that is a last resort attempt to clear the drain using a plunger.

I wish you luck and please let us know how you make out on this. If my answer was helpful please RATE MY ANSWER by clicking on the RATE THE ANSWER button below. Thank you!

Thanks for such fast response, I been boiling about 18 gal. of water now and pouring it down the drain. I can now run shower at full and drain is just keeping up with flow. It seems like it could be a little better so I am going to try the plunger again. The plunger never helped with old tub and this drain but maybe the boiling water has broken a lot of gunk up.

I am going to keep trying before dying my hair simoneaugie, but thanks :)

I think the culprit is built up soaps and body oils from slow draining over the years. Would you recommend trying to plunge with boiling water?

NO... not with boiling water! But hey, warm will work good I am sure. Seems like it is gunk/soap buildup for sure if boiling water increased flow! Good news.