Bathroom sink drain sloped downward?


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Old 02-23-24, 02:50 PM
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Bathroom sink drain sloped downward?

Had to replace the p-trap on an old bathroom sink and noticed the drain line was angled at a downward slope. Seeing as there is another sink on the opposite side of the wall that shares the same drain I think this is a bad setup, but wanted to check with the experts here.

Am I correct and I should cut that drain out and put a new one in at a slight elevated slope or parallel to the ground slope?


 
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Old 02-23-24, 03:15 PM
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It should slope 1/4" per ft in the direction of the drain. Turn your level end for end to make sure it reads the same way.
 
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Old 02-24-24, 04:33 AM
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Thanks for the help. So should it slope upwards towards the drain like it is or should it be the opposite and slope downwards towards the drain?
 
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Old 02-24-24, 05:09 AM
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Water flows downhill so that's the direction you want the slope. The pipe should always be pitched downhill to carry the waste water away.
 
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Old 02-24-24, 05:37 AM
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Ok, thanks, that is what I thought. So that drain portion is wrong.
 
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Old 02-27-24, 10:45 AM
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I agree the drain certainly should slope down "into" the wall. BUT... unless you're having drainage problems or clogs, I probably wouldn't bother trying to reconfigure the drain. The pipe goes into a fitting, which looks like it might be an elbow. It could be easy to cut the pipe in the wall and reconfigure... but if it's a sanitary tee going into the drain/vent, you'll be cutting out more pipe under the cabinet, which is a less-than-comfortable position to work in.

Sooo... evaluate whether the potential effort is worth the reward.
 
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Old 03-15-24, 12:47 PM
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Well, in fact it was clogging so needed to be redone. Don't want sink water sitting in the pipe like that.

I bought a reed tool reamer and it worked really well. First I cut the old pipe out flush with the fitting and then used the reamer to get out the rest of the old pipe. The PPR150 reed tool took less than 30 seconds to ream out the old pipe. Still have to put the new pipe in and slope it correctly.







 
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Old 03-16-24, 03:54 AM
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That PPR150 reed tool is awesome.
 
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Old 03-17-24, 05:41 PM
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Just to close out this topic, the new piping is in and has a nice gentle slope. Used plumber's putty on the sink connection and pipe dope on the other metal threaded connections along with the washers. Everything is water tight no leaks. Got a little messy with the ABS glue on the back wall near the drain fitting, but I am a DIYer after all . Thanks for all the help getting this sorted out.



 
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Old 03-19-24, 09:19 AM
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Very nice job! And nice to know you won't have to deal with clogs going forward.
 
 

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