plumbingsink
^^^ UPDATED PHOTO ^^^
I recently purchased a mobile home and have changed out the vanities in the bathrooms.
In the master the drain line was to low and had to extending the sink drain to hit that line, which was easy. But now the second bath the drain line is HIGHER than the P-trap.
Hopefully not busting into the wall to drop that line.
How do I fix this ?
Thanks in advance for any help.
No, there should not ever be two traps on a single drain line.
The point of the trap is to create a water barrier which prevents sewer gasses from coming up the empty pipe and into the house.
When you have two traps on the same line, you end up creating a kind of vapor block in the line which prevents it from draining properly.
What do you do?
Get yourself some 1 1/2" PVC (not CPVC, which is yellow, PVC which is white) with a 90 deg elbow, and also get two Fernco couplings (black plastic couplings with straps on each end that can be tightened) that will fit the pvc and iron drain pipe.
Use a metal blade on a sawz-all and cut out the p-trap in your basement. (Have a bucket handy!) Leave room to connect the Fernco coupling on both sides. I'd cut the right hand side out just past the coupling.
Measure and cut the PVC so that with the 90 elbow the ends line up with the newly cut drain lines. Glue the PVC together and confirm the fit, then connect to the old drains with the Fernco.
Viola - a proper drain line that will drain smoothly w/ no vapor lock.
If there were a trap there, it would have the same type of threaded fitting that your existing drain assembly has.
picture from Google Images
p.s.s.- I am dubious of your presumption that a trap exists someplace downstream
Best Answer
As long as your sink is above the drain it will work. Looking at your photo I would shorten the drain line from the wall. Make you get everything sealed or it will leak but it will work because the drain is below the sink bottom.