You've probably got only one pipe to the sewer line.
So, all your stuff shares the same drain.
It's all about volume vs size of the pipe
vs restrictions so one doesn't back up into the other.
If you try to drain both at the same time, you
may overflow something...maybe...
My mother had a washing machine with Sudsmiser. It must have had two
output hoses, one for the wash water, complete with soap, and another
for the rinse water. The wash water went into the laundry tub. The
rinse water went into a short pipe that fit into the laundry tub
drain, passing right through the tub full of wash water. (Maybe like
there were two drain hoses, there were also two drain speeds?? My
mother woudln't care if a load took 60 minutes instead of 45.)
So the sink drain was able to take the entire output of the drain pump
of the washing machine, without backing up. I also see laundromat
and apartment hookups with no laundry tub, so I guess they can take
the full output of the drain pumps too.
HOWEVER, in my house, the regular washing machine fills the laundry
tub to a depth of 10 or 12 inches before the drain starts to catch up
with the amount of water pumped out of the machine. Would it drain
faster for some reason if the drain hose went straight into the drain
pipe? Is there some siphoning effect that helps the drain along? I
don't think so because I think those apartment hookups aren't air-
proof at all. I think the bent drain hose just sits in the drain
ANYHOW, my question for you is, Is there any chance the clothes washer
drain will back up into the dishwasher, which won't be on and won't
drain until you turn it on. Is it possible for anything to back up
into the dish washer, or is there something that stops that? And
would the dishwasher part of the Y ruin siphoning that I speculated
helps the washer drain drain faster?
Sorry I can't answer any of this but there must be people who have
both connected like you want, or know the answers to my questions.
It all depends on what sort of laundry or apartment set up you
In a laundry often times the smaller machines are draining into
larger size pipes that you can not obviously see...
The larger industrial machines are either on their own 4" or 6" drain
lines or are emptying into a large drain trough located in the floor
behind the machines where you can't see it...
The answer is all about the "fixture units"...... a d/w is 2 (I
think) & a washing machine is 4 (I think).
Depends on the type of washing machine you have.
I had (& have) old school washers that used to dump into a laundry
The sink had a 1-1/2" trap leading to a 2" ABS line.
The sink would fill up rather deep but always kept ahead of the washer
unless the "cross" in the drain had lint buildup.
Lint buildup used to over flow the laundry sink a couple times a
The dishwasher was located about 15' away. The d/w flow "Y'd" into
the washer's drain line about 12' from each machine.
I never got a backup or overflow due to simultaneous draining but I'm
not sure how often they drained at the same time.
I measured the flow from the washer....my recollection.... the
discharge was about 30gpm
To be absolutely safe & sure..... you need to check the drain piping
size, determine its fixture units capacity & check that capacity
against the fixture unit demand of the combination.
here's a link to capacity
if my numbers (2 & 4=6) are correct and the info at this link is
correct (horizontal 2" line = 8 fixture units)
then you;re ok
Double check the numbers, I'd hate for you to have a flood. :(
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