Proper slope for drain line

Old 08-01-02, 08:32 PM
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Arrow Proper slope for drain line

I've got to run a new 4" drain line. What is the proper slope?
Old 08-01-02, 09:05 PM
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4" - 6" is good at 1/8" per foot, per UPC. Regardless, drainage fittings will already have slope built in, as long as you use them properly.
Old 08-01-02, 09:30 PM
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But 1/4" is better, if you can.
Old 08-02-02, 07:03 PM
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Now the correct answer

1997 UPC 1/4 per foot up to 4 inch over 4 inch 1/8 inch per foot with plumbing inspector aproval.
Old 08-02-02, 08:12 PM
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the self scouring capabilities of drainage piping works beast at 1/4 inch per foot. Piping 4" in diameter and larger can be run at 1/8 inch per foot WHEN THERE IS NOT ENOUGH fall to make 1/4 inch.
Old 10-24-02, 11:26 AM
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Proper slope?

Someone mentioned that proper slope was already built into the drain piping? Can someone explain that to me please?
Old 10-24-02, 12:48 PM
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The PVC fittings, i.e. elbows, T's, Y's, etc are biult with the appropriate slope built in this manner. A 90* elbow is not actually 90*. It is just a bit more than 90* (how much more needs a better mathmetician than I) so that if a percectly straight piece of pipe were inserted into it, it would drop 1/4" per foot. This does not however take flex of the pipe into account. I just did a DWV run that had a 30' horizontal run, so some care had to be taken to support the pipe well so that it didn't get any dips. If you are doing short runs where the pipe remains relatively rigid, the built-in slope should be plenty accurate for slope.

Old 10-24-02, 12:52 PM
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This is going to sound silly, but on your connections(Tee mainly), how do you know which side goes up then?
Old 10-24-02, 01:02 PM
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Tee's are installed in the direction of flow, in drainage, the direction the water flows in, in venting, the direction the air flows.

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