View Full Version : washer machine hookup

12-17-2008, 02:09 PM

I hooked up washer machines to the undersink plumbing before. Probably not up to code, but worked fine. I was wondering if anybody hooked up both a washer machine and dishwasher together to the undersink plumbing?

Gary Swart
12-17-2008, 02:45 PM
I'm not sure about code issues, but it doesn't seem to me to be a very suitable way to hook up a washer. In the first place, the dishwasher is not connected to cold water. Secondly, you really need accessible cut off valves for a washer. Then there is the matter of the drain for the washer. It needs to have a 2" standpipe that is trapped and vented.

12-18-2008, 06:43 PM
I'm talking about hooking the washer drain to the drain under the sink the same way a dishwasher drain hooks up. The supply lines would be tee'd off of the same supply to the kitchen faucet which would have shutoff valves.

I know it's not up to code to do it this way but I've done it before and it worked fine. However I've never hooked up a dishwasher and a washer machine together in this fashion. I was wondering if anybody has done it before and if it would work fine?

12-18-2008, 07:47 PM
Baaaaaaaaad idea.

Very, very, bad......

12-18-2008, 08:22 PM
I don't know all the code violations, of which I'm sure there are many, but I think you are going to have a major backup in your kitchen sink every time you do a load of laundry. The volume of water that a dishwasher holds is a fraction of the volume a washing machine holds.

12-18-2008, 09:12 PM
Dishwashers require a 1-1/2" drain line and trap.
Clothes washers require a 2" drain line and trap.

The clothes washer is 2 DFUs
The dishwasher is 2 DFUs

This would require the horizontal branch circuit that they both drain into to be a minimum of 2".

However, the clothes washer fixture drain is required to connect to a branch drain or drainage stack that is 3" minimum.

So what you are trying to do is wrong and not code compliant.

There are other factors involved such as the standpipe height where the washer connects and vent sizing.

Bottom line is that you are not suppose to do it that way.

12-19-2008, 06:14 AM
I understand that you are an inspector jar and it probably annoys you when you hear people rigging stuff like this.

I am asking if this would work and what would be the potential problems of this setup?

This kitchen sink has a two inch traps that drains directly into a vertical 4" stack about a foot away. Would it be okay to drain the washer machine into the kitchen drain above the trap?


12-19-2008, 06:33 AM
I think the reason it's allowed into a laundry basin is because of the depth of the fixture.

12-19-2008, 10:41 AM
I understand that you are an inspector jar and it probably annoys you when you hear people rigging stuff like this.

I am asking if this would work and what would be the potential problems of this setup?

This kitchen sink has a two inch traps that drains directly into a vertical 4" stack about a foot away. Would it be okay to drain the washer machine into the kitchen drain above the trap?


You're never going to get him to say it is "okay". If it works, you are going to do it, and I don't think the world is going to come to an end either way. :)

12-19-2008, 10:51 AM
I'm not trying to get him to say it's okay to do it, because it's not okay to do it if it's against code. I'm asking what would be the implications if one were to do it?

12-19-2008, 11:34 AM
Here's the implications. Clothes washers must discharge into a 2" trap. Close washers drain pipes must have an 18" stand pipe , minimum 42" maximum. Clothes washers must discharge by an air break into the stand pipe. Each stand pipe shall be individually trapped.

Does that clear things up?

12-19-2008, 12:12 PM
No, not really. You just pointed out all the requirements to set it up properly. I'm asking what would happen if I set it up the way I'm talking about.

12-19-2008, 12:19 PM
I'm sure someone will correct me if I'm wrong, but the implications are that all the filthy water from your dirty clothes and loaded diapers will back up into, and overflow out of, your clean kitchen sink--the same sink you will be washing your vegetables to put in your Crockpot.

12-19-2008, 01:01 PM
Why don't you just do what you want to do because you are going to do it anyway.

Many things will "work" but that does not mean that they are done the right way.

There are codes for a reason.

Why can't people just do what is required? Is that so difficult? Are we becoming that lazy?

12-19-2008, 01:05 PM
Actually it was already done a long time ago, I was just asking about opinions and worst case scenarios.

It comes down to the amount of money to be spent to replumb a 2 inch line in an existing kitchen. It's very disruptive and can get very expensive. Why is that so hard for you to understand? It's pretty simple actually.

Also, I wouldn't consider the bottom of my kitchen sink clean. It's probably one of the dirtiest and infested parts of your house.

12-19-2008, 01:08 PM
The right way will be more expensive in your case but it is still the right way.

You were given information from multiple people telling you not to do what you were planning on but you continued to prod looking for "approval" as many people do.

Eventually someone will tell you what you want to hear.

Sorry doing things the right way will not be the less expensive option but it is the right way. You follow your own ethics and local laws.

12-19-2008, 01:12 PM

I'm not asking or looking for approval. I ask this question again, as I already asked it many times and have not received any answers.

What are the downside risks, specifically, to doing it that way? What can happen? Give me specific details and don't just say it's not the right way to do it.

If you don't know the answer, that's okay, just say you don't know.

After knowing the downside risks at least at that point I can make an educated decision to leave things the way they are or change them.

12-19-2008, 01:50 PM
Jar, your wasting your time. Whatever reasons given don't make a bit of difference. So here's the reason. When the you know what hits the fan and there is property damage done and you try to claim it on your homeowners insurance, with luck they will tell you to screw.

12-19-2008, 01:52 PM
Downside risk is that you could overflow the sink and ruin the floor. You could backflow into the dishwasher and contaminate the inside and also have it spill out onto the floor.

Too expensive? Having to replace your dishwasher will cost more than the correct plumbing. Having to replace your floor will cost more than the correct plumbing. If you ever decide to sell this home you will likely be required to properly re-plumb before selling.

12-19-2008, 02:27 PM
You can discharge into a kitchen sink from the top like you would into a laundry tub and you would be fine; its done with portable units all of the time since you still meet the air gap requirement.

You can connect into your existing sink drain between the sink trap adapter and the p-trap, providing that its all 2" piping for the trap arm (I can still get away with 1.5" piping for a traditional clothes washer, but the newer style units require 2" piping as they discharge like commercial units). But this type of installation is really ill advised; it is done with a laundry tub because the laundry tub is deep enough to handle any backup, but doing it with a kitchen sink would not only put you at risk of flooding if the basins filled up, but you would put your dishwasher at risk of backflow, and at the very least you would definitely get a mound of suds backing up into your sink basins every time the washing machine discharged as well as contaminating your sink with filthy laundry water. And even if you were able to squeeze in another fitting for your laundry standpipe connection, you would still have to meet the standpipe requirements.

Your best bet would be to cut open the wall in your sink cabinetry, and install a tee below your sink trap arm in the kitchen sink stack and run a wet vented trap arm out to the standpipe (if wet venting is allowed where you are).

But you really should install and vent a stand pipe properly into a proper wash box behind where the laundry unit is going to go. Like everyone else is telling you, it will cost you less to do it properly in the first place than it will to pay for repairs and grief later on.

12-19-2008, 04:09 PM
Why not just bust a window and stuff the hose out the hole.
Thats a lot easier than what you are talking about!
It's not to code either but who's worrying about that crap!:mad:

12-19-2008, 06:12 PM
The only educated response and the only person who actually answered my question was Basement Lurker. Thanks for the feedback.

The rest of you guys don't know how to talk to people. You are all trying to be funny but are not succeeding. I simply asked why it wouldn't work or why it's not a good idea. I said it myself from the beginning that I know it's not the best idea or up to code.

nmaster, you sound like a bitter old man.

redwood, do you have anything constructive to add?

I started on this forum a couple of days ago and immediately notice that you are not the friendliest group of people. I've been on the JB forums for a while and let me tell it's the exact opposite.

12-19-2008, 06:38 PM
It is not a good idea because it is not compliant with standard plumbing techniques or the required plumbing codes.

The problem is the amount of DFU's as I stated in my original post. Undersized pipe has an increased chance to backup. There are other issues with the standpipe requirement heights as mentioned by someone else.

I am not trying to be funny, I am trying to help by telling you what needs to be done by giving you specific information in order to properly make a connection.

As far as your concern of "what if?", I don't have a crystal ball nor do I want one when it comes to health and safety requirements and my job.

I enjoy offering help to those who need it and want to take direction from myself or others who give proper advice. That is why you are here is it not?

Pull a permit and get the work inspected.

12-19-2008, 07:33 PM
This is a plumbing forum and I know if you bring anything else to the table it will be held to the same standards, and yes, those are regulated by codes written and enforced for the public's safety and well being. The day our standards for potable water and sewage go to the wayside is the day we take a step back in our own evolution.

12-19-2008, 08:08 PM
I thought I was being constructive....
You came here and asked if you could do your plumbing in a manner that is not to code. We told you No!
However, you don't like the answer and you are shopping for a different answer that you are not going to get.

The plumbing code has several reasons for being in existance.
1.) It is tried and accepted manners of plumbing that work with a high degree of reliability.
2.) It is methods that are used that protect your health from possibly ingesting waste or breathing harmful gases from waste.

If you don't want to accept our answer fine go right ahead and eat poo but don't waste our time asking us. If you don't want to do it right then do take the easiest way out by all means.

Break the damn window and stick the hose out the window. Breaking the window is easier than opening it.

http://i44.photobucket.com/albums/f2/Redwood39/1021197217456cae4d8f4a2.gif http://i44.photobucket.com/albums/f2/Redwood39/deadhorse.gif

12-19-2008, 09:47 PM
People come here to get free advice from professionals, and when they don't hear what they want to hear, they cop an attitude and start insulting folks that are trying to help them!


That's why this site is so great! Not only educational, but great entertainment value to boot! Rock-on...

12-20-2008, 03:57 AM
If you came here for absolution then you have come to the wrong church.

You recieved many good answers to your question. All of them you have found a way to refute in your mind. Plumbing is a science and a profession. Even the lowest apprentice knows better than to drain a pressure fixture into the set up you have described. If you feel I am a bitter old man, perhaps it's because all of my career I have had to deal with folks like you that place dollars and expediancy over accepted plumbing practice. We're you truley expecting a pat on the back here? A, hey, why didn't we think of that, what a great idea? I'm sorry that your were not pleased with the responses but then, you should have known better in the first place. There are several other forums out there, why not see what kind of response you get there? I'll bet it is very much the same. We are professionals. We are not going to steer you in the wrong direction nor are we going to condone bad plumbing.

12-20-2008, 09:13 AM
I simply asked why it wouldn't work or why it's not a good idea. I said it myself from the beginning that I know it's not the best idea or up to code.

Posting on a plumbing forum about hack plumbing may not be the best idea.
The plumbers with experience will try to persuade you to do the right thing. That doesn't make them bitter, they are just trying to protect you and your neighbors.

When someone hacks plumbing, it not only affects them, it affects everyone that uses that water source. Water is a community property and responsibility.
You wouldn't want someone to pee in your coffee water.
And yet you are suggesting that you would like to do a similar thing to your neighbors.

It's not that hard to cut the back of the cabinet and expose the plumbing to get the right fittings in there.
I've lived in places where the plumbing was cut in to the kitchen for a washer, and I've plumbed in washers for others off of the kitchen line.
But it was installed to code, with a plumbing permit, and inspected.

It would take you "less" time to do it right, then to find ways to do it wrong.

There is something very disturbing about that way of thinking.

Since you like learning about this stuff, just kick it up a notch, and start asking how to do it right. You will like the answers a lot better.

But in the meantime, we're having fun too.
In the construction trades, you have to have a thick skin too. It's how they "broke" us and got us to listen and learn.
And then we pass the lessons down to the next generation.
Merry Christmas.

12-20-2008, 02:20 PM
are you hooking your dishwasher up w/out an airgap? Because the answer to what will happen is water will back up into your dishwasher from the wasteline. When the washing machine discharges your sink will fill up w/ water and depending on how much crap you put down your disposal black gunk and rotted food waste will constantly line the rim of your sink causing you or your wife a great deal extra unneeded grief.

Top it off, go to sell your place and you will have to redo it the right way anyways before you can sell the property.

Your idea sounds bad just from a logical perspective. Sometimes codes are hogwash, but most of the time there's a real reason for their existence. Usually it's because someone like you does exactly what you want to do right now. Someone gets sick or hurt or property gets ruined.

In the end it's a waste of effort not to do something the right way the first time.

12-20-2008, 04:15 PM
My questions have been answered. Thank you. I'm in NYC and I rarely see any plumbers use an air gap with the dishwasher, they just create a loop and feed the hose high up through the cabinet under the countertop.

I never understood the air gap because on the bottom of the dishwasher where the water comes out to wash the dishes is above the overflow point, were the dishwasher to fill up with water it would spill on the floor, no?


12-20-2008, 04:32 PM
With a loop all that has to happen is for the water to pass backwards through the loop, then it will pull all the water until it's all in the machine(capillary action). An air gap eliminates that possibility. IF it does come out of your airgap, you have it directed to eject into your sink so that you know somehting is wrong when it happens. Usually it's food particles collecting in the hose to the disposal.

If the loop is below the counter top level then if the sink fills to the top it would be possible for the water to crest backwards in the loop. A sink stoppage combined with an emptying cloth washing machine would fill the sinks, over flow the sinks onto your floors, and crest that loop under the counter causing water to go backwards into the machine. Cloth washing machines are really good at showing you a stoppage you won't see through normal usage due the the sheer volume of water displaced all at once.

12-20-2008, 07:26 PM
Isn't the height of the dispenser in a dishwasher higher than the overflow level? Wouldn't that prevent drain water from entering the supply of the dishwasher?

12-20-2008, 08:21 PM
It wouldn't back up into the hot water supply line to the dishwasher. The loop you have is below the actual rim of the sink. The loop I have seen used in some diagrams for Bosche dishwashers and some others but it's always in conjunction w/ an airgap. If you don't have the airgap and your drain stops up, you fill up the entire drain from the stoppage to the rim of your sinks so they are completely full. This means the full weight of the water in the sinks is pushing downwards and can't go down the drain, so it pushes itself downwards wherever it can go. With the loop being below the countertop, there's 2 inches or so of water that can sit in the sink above the loop and can push it's way into the loop. Once it makes it over the hill, it can then pull the rest of the drain water with it into your empty dishwasher leaving you a nice pool of nasty water in the bottom inside of your dishwasher. The airgap breaks that chain of events by putting the pathway above the max waterline at the top rim of your kitchen sink. It also breaks the solid tubing so that capillary action can't draw the wastewater backwards into the machine.

The machines waste line is connected at the bottom of the machine to a little pump. I have no idea if they have a backflow valve built in to prevent water from coming backwards from the drain into the machine. If they do, I'd seriously doubt they are strong devices.

This is a worst case scenario for sure. But older houses will do things like this. And few people know their drains are extremely restricted until they fill up their sinks to the top and let em drain. I have seen many times where the customer's have stoppages in their 2" horizontals from their kitchens and only find out about it when their family come over to stay w/ them, increasing the amount of laundry use.

With your idea, you are most certainly going to see a backup of water in your sinks regardless of how open your drains are. Over time you'll see the line it reaches raise incrementally until one day it's all over your floor and the sinks won't drain. At this moment you are at risk of the water going back into your dishwasher w/out an airgap, even w/ the loop because the loop is still underneath the countertop.

12-20-2008, 08:29 PM
how come plumbers in NYC don't use an air gap and just put a loop under the countertop? These are master plumber's and I rarely see an air gap. There must be some reasoning behind this.

I'm just talking about dishwasher being hooked up to the sink drain. Forget about the washer machine. I'm convinced that it's a really bad idea for the reasons you cited.

12-20-2008, 08:39 PM
It's not always code to use an air gap in many places. In those towns, high-looping the DW drain under the sink is an acceptable alternative.

I prefer it myself, because food particles inevitably clog the drain where it attaches to the G/D, and with an air gap, the entire contents of the dishwasher drains onto the floor. Seen it dozens of times in the apartments I've worked at, where air-gaps were used.

Although, a legitimate concern, I've yet to see cross-contamination from a sink back-up, which is the main concern to high-looping.

12-20-2008, 08:49 PM
^exactly. I'm a a trained monkey so I stick to how I've always done things. But Verdeboy is right, it's not mandatory in all locals and you usually do get a build up of food gunk in the hose from the gap to the disposal which one day leads to the water coming out the airgap. I only see it hit the floor when a woman decides the airgap is ascetically unappealing and turns it to face the wall causing the inevitable flooding to go everywhere instead of just into the sink.

The house I just moved into had a mickeymouse diy'er put in the kitchen and I think he forgot to knock out the plug on the garbage disposal. My water from my dishwasher has been coming out of my airgap since I moved in. I only noticed it the other day and wondered why my wife didn't bother to mention it before now. It hasn't hit my floor once, but I'm sure if my wife had turned it around, it would be a whole-nother story.

12-20-2008, 09:07 PM
My water from my dishwasher has been coming out of my air gap since I moved in. I only noticed it the other day and wondered why my wife didn't bother to mention it before now. It hasn't hit my floor once, but I'm sure if my wife had turned it around, it would be a whole-nother story.
You're lucky. A lot of people keep their sink full of water to soak pots and what not, so even if the hole in the air gap was pointed into the sink, you could still have a flood on your hands.

12-20-2008, 09:59 PM
My wife's a clean freak so our dishes are put away as soon as we use them. If people have full sinks and are running the dishwasher at the same time, they have problems of a whole different nature in my esteemed opinion ;).

You are spot on, everyone does things differently. My dad always said you gotta test everything out w/ the most abusive usage possible in mind.

12-21-2008, 05:20 AM
New Hampshire allows the loop and clip method. I have been fighting against it for years. Looping and clipping does nothing to protect from backflow or siphonage. Besides, many if not all newer dishwashers already loop the drain up the side of the appliance in manufacture which essentially creates a double trap situation if the is again looped and clipped.