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 Max Pitch for Washer Drain?
Author: Fixitangel (NC)

Hi; Generally, the minimum drain line pitch (fall) for a 2" washer drain is 1/4" per foot. Yes? If there was an 18 foot run for a 2" washer drain that had an 18" drop, (1 inch per foot) Would that be OK, or too much pitch? (the drain WILL tie above into a bathroom 3" vent)
Is there such a thing as TOO much fall on a Vented drain run?
Sincere thanks.



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 Re: Max Pitch for Washer Drain?
Author: chicago plumber (IL)

i dont think there is a thing as too much pitch. the more the better.

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 Re: Max Pitch for Washer Drain?
Author: LemonPlumber (FL)

Well our codes just changed to dis agree with the over eight feet on two inch is wrong.We now have ten feet.at 1/4"per foot the pipe at eight foot,the flow should cut off it's hydraulic level at pov.We also have been allowed to reduce the pitch to 1/8"per foot on 2" so may be too much fall is bad.The washing machine discharge is a hard to minimize fixture.Could you change this long run to 3"?/lessing the effect of foamed flow?.Any vent below your tie in point would be bubbled/cut off.Include major fixtures.



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 Re: Max Pitch for Washer Drain?
Author: PlumerDan (CA)

you discanbobulated your math...1/4 in. per foot is 4.5 in grade. but if you have the room 1/2 per foot is better on a washer drain..1/4 is code minimum,there is no max.

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 Re: Max Pitch for Washer Drain?
Author: Fixitangel (NC)

Sincere thanks for your reply. Good to know there is no max. This would be a job in a crawlspace from, well, you know where, so it is good to learn before I slither back into the hole! :)



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 Re: Max Pitch for Washer Drain?
Author: hj (AZ)

As long as the vent is within the required distance from the trap, there is no maximum pitch. However, in you example, the vent would have to be less than 2' from the trap.

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 Re: Max Pitch for Washer Drain?
Author: Fixitangel (NC)

Thanks, HJ. A 2" vent will rise up next to the trap and hook into a 3" roof vent, it's good to know there is no max fall on the drain. Faster drain the better huh?

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 Re: Max Pitch for Washer Drain?
Author: steve_g (CA)

No one has ever had to clear a drain that plugged up because of 'too much pitch'.

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 Re: Max Pitch for Washer Drain?
Author: Shoemaker2 (MA)

We were taught too much pitch would leave paper and solids behind and that is why pitch was to be kept at a constant grade and not more than 1/4" per foot. In the case of a washer I could see that it is not as much a concern.

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 Re: Max Pitch for Washer Drain?
Author: CHayn (IL)

too much pitch could make the pipe enter your fittings at too much of an angle. Make sure you have a good connection! Good Luck!

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 Re: Max Pitch for Washer Drain?
Author: hj (AZ)

You were taught wrong and never learned the truth.

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 Re: Max Pitch for Washer Drain?
Author: jimmy-o (CA)

That subject has been studied over the years, and from what I have read in places like PMEngineer and IAPMO's 'Official', it has been refuted. Testing apparently does NOT support the theory that the water will outrun the waste.

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 Re: Max Pitch for Washer Drain?
Author: packy (MA)

then how do they explain sluicing for gold? lighter objects flow while heavier are left behind.

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 Re: Max Pitch for Washer Drain?
Author: hj (AZ)

They are being trapped by a dam, either by a sluice box, or swirling the pan, and the water is allowed to run off. If it were true, then the gold would have been left behind as soon as the stream took a steep downturn, and you could go up to the first dropoff and pick all the gold you wanted to.

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 Re: Max Pitch for Washer Drain?
Author: jimmy-o (CA)

Yes. The pan has ridges around the wall, which in the hands of a skillful panner give you the same effect that happens in the streams...heavier stuff is slowed down by the interference of the ridges or the rough bottom of the stream bed.

And of course, in a sewer pipe, any interference points DO collect wastes, especially something like paper or other debris which can snag on something.

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 Re: Max Pitch for Washer Drain?
Author: royboy (SC)

The IPC minimum pitch for a 2" washer drain line is 45 degrees. You can use 2" pipe for verticle which is 45 or more degrees. Anything 44 degrees or less must be 3" or larger.

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 Re: Max Pitch for Washer Drain?
Author: chicago plumber (IL)

old timers and their plumbing urban legends.

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 Re: Max Pitch for Washer Drain?
Author: dlh (TX)

royboy, what are you talking about? 45 degrees pitch as a minimum? not in any ipc code book i have ever seen. in fact i have never seen a code mention degrees for slope. i have seen engineers use 2% slope for utility piping but nothing in a plumbing code

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PLUMBERS "Protecting The Health Of The Nation"

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 Re: Max Pitch for Washer Drain?
Author: Fixitangel (NC)

Thank you. You are so right; an 18' straight run at 1" per foot would not line up correctly at the ends. I'll have to use a pair of 22-1/2 degree offset unions somewhere in the middle where a floor beam support exists in this little crawlspace from he**. In some places there's only 10" to wiggle under. I appreciate all advice before I slither back into that hole!

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 Re: Max Pitch for Washer Drain?
Author: dlh (TX)

they dont have to be placed in the middle. you could offset the line anywhere you want between the 2 points

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PLUMBERS "Protecting The Health Of The Nation"

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 Re: Max Pitch for Washer Drain?
Author: hj (AZ)

Too much pitch makes it too slippery for the alligators to walk up the pipe.

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 Re: Max Pitch for Washer Drain?
Author: LemonPlumber (FL)

Set the offset as close to the fixture drain as possible.It will reduce draw own on foaming.

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 Re: Max Pitch for Washer Drain?
Author: royboy (SC)

I was refering to the fact that 2" pipe can only be used in the verticle. 45 degrees is verticle so less than 45 is horizontal and must change to 3" pipe for the horizontal run.

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 Re: Max Pitch for Washer Drain?
Author: dlh (TX)

oh

you say that is in the ipc? what section? because i havent seen it

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PLUMBERS "Protecting The Health Of The Nation"

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 Re: Max Pitch for Washer Drain?
Author: hj (AZ)

I've always thought that ANYTHING which was not horizontal was NOT horizontal, and now I find out that it is still horizontal until it reachs 46 degrees. I guess that means that when I offset a low vent at 30 degrees using a 1/6 bend, the inspectors are going to have to start rejecting it because it will not evacuate properly. Not likely to happen.

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 Re: Max Pitch for Washer Drain?
Author: royboy (SC)

Yep, I learned that in the annual required code class about 3" pipe on wash machine horizontal drains. A 45 bend or more is considered a verticle offset. Anything less than 45 is a horizontal. The instructor said they were told to warn the plumber on the first time but after that, it's a red tag. I have one inspector who turned me down on putting a hanger on a 3" vent at 4'-4" so they are IMHO too nitpicky on some things.

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 Re: Max Pitch for Washer Drain?
Author: dlh (TX)

ok, you made me go look it up.

as far as the 2006 ipc is concerned

section 406.3 says, "the automatic clothes washer fixture drain shall connect to a branch drain or drainage stack a minimum of 3" in diameter."

it makes no mention whether the 2" line can or can not run horizontal before having to tie into a 3" line

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PLUMBERS "Protecting The Health Of The Nation"

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 Re: Max Pitch for Washer Drain?
Author: royboy (SC)

We were told that this issue is clarified in the 2009 amendments. By the way dlh, I appreciate a lot of your answers. They show that you have run into some interesting problems. Keep up the good work!



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 Re: Max Pitch for Washer Drain?
Author: dlh (TX)

ah, well then that would explain my ignorance since my area has at least another year or 2 under the 2006 code before cities start reviewing their charters (which is when they usually change their codes if at all)

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PLUMBERS "Protecting The Health Of The Nation"

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 Re: Max Pitch for Washer Drain?
Author: LemonPlumber (FL)

A branch drain with or with or without offsets or sub sections ?SEE Horizontal branch.

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