Does this dishwasher drainline need to be changed?

[Gary Swart]

If you can explain to me just how it would be physical possible for water in a clogged drain could rise above the level of the sink and into the looped washer hose, I will gladly eat crow. Now I realize as a professional you are required to follow local codes and use an air gap where code requires, you must admit that air gaps are not required everywhere. I sure don't want to start a stupid war over this, so this will be my last comment to this question.

 

[Verdeboy]

I'm on your side, Gary, but here are two ways it is theoretically possible for the water to backflow over the high loop into this dishwasher.

1. The backup comes up to and over the rim of the sink.

2. You have pots or dishes blocking the drain, forcing the contaminated water to follow the path of less resistance.

 

[Sponsor]

 

[Geniescience]

is this new and original? the idea of plumbing it in the drain pipe with a disposer

umm, I think it is good to let Master Plumbers keep their approach to public safety, and let air gaps "exist".

What I cannot figure out, is why nobody has ever suggested plumbing the Teed'd-air-gap in the drain pipe "below the sink but above the trap" when you also have a garbage disposal!. It works for the situation where there is no disposer, so why is it never suggested for a "with disposer" situation?

What am I missing here?

David

 

[AdrianMariano]

I don't think I understand why the "teed air gap in the drain pipe" is any different than just having the garbage disposal act as an air gap.

I'm also not sure I understand why it's bad to have the dishwasher drain line go through the basement. I mean, will there be that much less water sitting in it if I route it behind the cabinets? Presumably the water that's going to be sitting in there is the rinse water anyway.

Is my installation bad because it (1) goes into the basement or (2) because it hangs down so low, or (3) because it has several different kinds of pipe.

If (2) I could easily change it by installing a new hose that I attach to the joists in the basement so it's not hanging down so low. If (3) I could get a new hose long enough to make the full run. If (1) then it's considerably more work as I have to figure out how the hose can be routed through the cabinets and drill holes through the cabinets and such. I don't want to do that unless there's a good reason to go to all the trouble. (I'm supposed to finish this job in one day so we can use the kitchen again.)

How sharp of a bend can the drain hose make without causing trouble?

Yes, the drain needs to be totally redone. The fact that the DW is some distance from the sink is really irrelevant. You just run a hose through the back of the cabinets to the sink. I see no reason why the hose could not be under the floor.

I'm a little confused by this. Right now the hose is under the floor, which appears to be considered part of the problem.

 

[Dunbar Plumbing]

I don't think I understand why the "teed air gap in the drain pipe" is any different than just having the garbage disposal act as an air gap.

I'm also not sure I understand why it's bad to have the dishwasher drain line go through the basement. I mean, will there be that much less water sitting in it if I route it behind the cabinets? Presumably the water that's going to be sitting in there is the rinse water anyway.

Is my installation bad because it (1) goes into the basement or (2) because it hangs down so low, or (3) because it has several different kinds of pipe.

If (2) I could easily change it by installing a new hose that I attach to the joists in the basement so it's not hanging down so low. If (3) I could get a new hose long enough to make the full run. If (1) then it's considerably more work as I have to figure out how the hose can be routed through the cabinets and drill holes through the cabinets and such. I don't want to do that unless there's a good reason to go to all the trouble. (I'm supposed to finish this job in one day so we can use the kitchen again.)

How sharp of a bend can the drain hose make without causing trouble?



I'm a little confused by this. Right now the hose is under the floor, which appears to be considered part of the problem.

Do you know what the words "industry standards" means?


Do you think that massacre of a setup you have would pass in any state?



You've taken a mere simple situation, complicated it, over analyzed it to death when a plumber could of come in and made mince meat of that hack job.

This thread is certainly not useful to the attending audience by any means. It's merely portraying the short cuts your trying to get away with and the ones who are trying to help are TRYING to put you in the right direction.

Plain and simple, you're not cut out for the job.

 

[AdrianMariano]

Most of the discussion in this thread has been about air gaps, which I think probably has been useful to the audience. I feel like I have a pretty good understanding of the air gap now, though I'm a little puzzled by this "teed air gap" someone brought up recently which sounds to me like no air gap at all.

My house is over 50 years old. It's full of things that don't conform to current industry standards. That's life. I can't rip out the entire plumbing system and replace it with a modern one that conforms to industry standards, just like I can't make the basement stairs have a conformant rise and run. That's how it is with an old house. But this means that something beyond mindless conformance to modern standards is required. I need to understand how things work. (In my opinion the people who are not cut out for the job are the ones who undertake the work without understanding.)

So what specifically is wrong with my installation? It has a high loop which is code some places, as I understand it. Does code prohibit a dishwasher draining through the basement? Or it prohibits using multiple types of pipe? Obviously nobody would come in and install something that looks like what I have. But that doesn't necessarily mean that there's something wrong with it from a functional perspective.

It's often said: If it ain't broke, don't fix it. I'm trying to figure out if it's broken or not. (The dishwasher seems to drain OK, after all, and the drain line doesn't leak.) If it's not broken, my inclination is to follow the advise of the aphorism. It doesn't always make sense to replace legacy systems with new systems when the legacy system is working OK. I hadn't initially planned to do anything involving the dishwasher simply because it wasn't in the scope of the effort which was limited to stuff under the sink. I'm replacing the sink, not the dish washer. I'd be willing to bet that if I hired a plumber to come in and do the job for me that nothing about the dishwasher drainage would change.

That said, if there is a good reason and it's possible, I'll run the drain line through the back of the cabinet. But I don't want to do it just for the heck of it to make more work for myself and introduce more things that could go wrong. I don't think I have seen yet an explanation of why it would be better to run the drain line through the cabinet vs. putting in a new drain line that is fastened to the joists in the basement (and hence is a horizontal, rather than hanging down with the big dip). The drain line through the basement would be shorter and straighter. That's bad?

 

[Verdeboy]

Is it up to code? No. Is it functional? Yes. There's an old saying, "Worst first." You probably have many other projects that require your attention more than this. If it ever starts leaking, it may be a good time to re-do the drain.

PS: Just don't expect a group of professional plumbers to give their blessing to a rigged system like that.

 

[TedL]

As for safety, I believe the air gap at the dishwasher provides protction against cross connections.

I, like the originator of this thread, like to understand the reasons for things, so I can apply the principles in other situations and evaluate the need/urgency for corrective action. I realize this puts additional "work" on the pros who help out here, but I, for one, really appreciate it when it happens.

Example: In the city next to where I live, plastic piping is not allowed. Reason for the rule: A strong union influence.
What happens if plastic is used? Depends on whether the work will be inspected.

(BTW, the originator sounds like an IT systems analyst who is used to asking users "why" so that he can design a system to meet their actual needs, not just automate the currrent (often manual) processes. It's a good thing...really!)

 

[AdrianMariano]

I'm not asking for a blessing. I want to know what specifically is bad about it so I can decide whether it's important enough to do something about it when I redo the kitchen sink. Since I'll be disconnecting the hose at the disposal end this is a reasonable time to ask if I should do something about it. On the other hand, I'm not letting the project expand into a wholesale replumbing of the house. I know my existing dishwasher drain is not ideal, but just how wrong is it and what problems could it cause?

Specifically how is it not up to code? There appears to be a decrease in the size of the pipe when it goes from the white hose (5/8"?) to what looks like 1/2" copper. That would presumably be a violation as drain lines are not supposed to shrink. But is that it?

 

[Gary Swart]

As I previously stated, I'm not sure what is technically wrong with running the drain hose under the floor, but the sag is bad and the splice is not good. What you probably can do to make this somewhat more acceptable is to replace the hose from the DW to the drain with automotive heater hose, probably 5/8", all in one piece. Fasten it to the joists so it runs in a straight with no dips. Also, if I read your photos correctly, there is a valve in the drain line. Get rid of that. Make sure the loop is as high as possible and attached to the underside of the counter in such a way that it will not kink. If it's any consolation, my DW supply line tee off the the main hot water line in the basement with a valve then a flex line runs through the floor to the washer. Not exactly textbook, but functional.

 

[AdrianMariano]

Also, if I read your photos correctly, there is a valve in the drain line.

It's not quite that bad, though the picture sort of makes it look like it. That valve is the for the dishwasher supply which sounds like it's run just about the same way as yours. There's a compression union and it goes down to thin flexible copper tubing and goes up through the floor. (Actually the compression union is covered with green crud which I think means it must be leaking a little, but not enough that I ever see it wet.)

Two questions about your suggestion:

1. Why is an automotive heater hose a better choice than a dishwasher drain hose?

2. Why 5/8"? Right now the second half of the drain line is 7/8". Isn't bigger better?

 

[Markts30]

Two questions about your suggestion:

1. Why is an automotive heater hose a better choice than a dishwasher drain hose?

2. Why 5/8"? Right now the second half of the drain line is 7/8". Isn't bigger better?

Don't know that automotive hose is better but might be easier to get...
Supply houses will have washer hose by the foot and you can buy the 10 or so feet you will need..

As far as the 5/8", might be he is referring to automotive hose ID (inner diameter) as opposed to the 7/8" OD washer hose (outer diameter)...

 

[Geniescience]

you got your answer

adrian

just a note to confirm -- you got your answer, which is that you could leave it for now and get around to it when it leaks if it ever does. But no individual will go on record as having recommended you do that. (No blessing asked for and none given.)

my point, which may not be relevant to you, was to get rid of the passage through the disposer by teeing into the kitchen sink drain above the disposer's Tee. Umm, is that original or not? I don't know, I really don't know. But if it is do-able, then it gets rid of the safety issues which a separate air gap will take care of.

David

 

[TedL]

The smooth interior of the heater hose would provide less resistance than the corrugated DW hose.

 

[Gary Swart]

My thought on the automotive hose was it comes in whatever length you need and since it is capable of handling hot water under pressure, it would certainly be OK for a DW drain which has no pressure. The size would depend on the size required by you DW and the tail piece at the drain and may or may not be 5/8". I was unaware the regular DW drain hose was available in long lengths, and that may be the way to go in order to properly fit the DW and tail piece. Don't get hung up on the automotive hose, get what will fit.

 

[AdrianMariano]

I have to admit that I was wondering if those corrugated dishwasher hoses were somehow smooth inside. Regarding dishwasher hose availability, I had noticed this mail order source which has 5/8" and 7/8" hoses available:


But I hadn't looked at local suppliers to see if they are available there. (For all I know the above site is just selling automotive hoses as "dishwasher hoses")

just a note to confirm -- you got your answer, which is that you could leave it for now and get around to it when it leaks if it ever does. But no individual will go on record as having recommended you do that. (No blessing asked for and none given.)

Actually I'm still a little hazy about the answer to my basic question: why is my installation bad. Everyone seems to agree that it's terrible and needs to be changed, but nobody seems able to actually say specifically what is wrong with it. Are you saying that the answer is that it might leak due to all those extra splices?

my point, which may not be relevant to you, was to get rid of the passage through the disposer by teeing into the kitchen sink drain above the disposer's Tee. Umm, is that original or not? I don't know, I really don't know. But if it is do-able, then it gets rid of the safety issues which a separate air gap will take care of.

I don't think I understand this. Why is passage through the disposer bad? (Because the disposer might be full of crud?) So the idea is to tee into the other drain that doesn't have a disposer on it? Without a conventional air gap of some kind couldn't such an installation siphon water out of the sink back into the dishwasher?

 

[Rancher]

Actually I'm still a little hazy about the answer to my basic question: why is my installation bad. Everyone seems to agree that it's terrible and needs to be changed, but nobody seems able to actually say specifically what is wrong with it. Are you saying that the answer is that it might leak due to all those extra splices?

If you didn't think something was wrong with it in the first place, then why'd you ask? Personally I like it, I think you should leave it alone! Let's take a vote.

Rancher

 

[Verdeboy]

Actually I'm still a little hazy about the answer to my basic question: why is my installation bad. Everyone seems to agree that it's terrible and needs to be changed, but nobody seems able to actually say specifically what is wrong with it. Are you saying that the answer is that it might leak due to all those extra splices?

IMHO, even if it never leaks, it's messy, sloppy, ugly, inefficient, and denotes poor workmanship.

 

[AdrianMariano]

If you didn't think something was wrong with it in the first place, then why'd you ask?

Verdeboy wrote:

IMHO, even if it never leaks, it's messy, sloppy, ugly, inefficient, and denotes poor workmanship.

So why'd I ask? What it really boils down to is that it looks bad. It's ugly, as Verdeboy says. Does that mean bad function? That's what I was trying to find out. I have, on the one hand, an inclination to change it for essentially aesthetic reasons and an opposing desire not to overcomplicate the job that I'm hoping to finish in one day. Understanding the functional concerns about the setup (if there are any) could tip me one way or the other on whether to change it or leave it.

 

[Geniescience]

if I had all the answers...

adrian

i like your persevering attitude.

If I knew all the reasons why a multipart multimaterial hose were deemed bad, I might be already making a living as an exam-question writer for Master Plumber certification exams. Example: "List all seven reasons why ... is dangerous."

You asked "Are you saying that the answer is that it might leak due to all those extra splices? "

Can we agree that we both don't know for sure but that we both think that that is a sufficient reason -- all by itself -- to agree that the pipe could be deemed not up to snuff if it were for a new installation being prepared for a new buyer who would be expecting a clean and professional installation? I think so. Can we agree that "Code" is designed to produce that level of cleanliness and professionalism? I think so. Is there more? I don't know for sure, but I think we have studied this enough to wear out just about 99% of the population, if anyone is following this thread. Even the most dogged scientific researchers could ask why we want to know more.

If there were any other reason More serious, you would have heard it by now, I believe. Anyone can correct me if I have missed something important. I know for sure two things: 1.) it works for now, and 2.) you asked if consensus would be in favor of your changing it, and why.

Next subject. "Why is passage through the disposer bad? (Because the disposer might be full of crud?) So the idea is to tee into the other drain that doesn't have a disposer on it? Without a conventional air gap of some kind couldn't such an installation siphon water out of the sink back into the dishwasher?" -- Yes. Almost. Not quite. Close. The disposer may be full, and or it may do other bad things, and or the sink and or the dishwasher may also do bad things. Cross-connections and backflows possible everywhere. Rarely happens but can be fatal, lethal, deadly. It can be a matter of life or death. That is what plumbing is about. In my view, it is more complex than electricity which is also extremely dangerous.

Look at any installation with NO disposer, and then look at my remarks as saying "can we do the same thing WITH a disposer present, by just not going through the disposer?" I am not a plumber so I ask without knowing the answer.

Drinking water never kills anyone, until suddenly one day it kills people. Contamination. Sewer gases never kill anyone until suddenly they do. That's plumbing! (Sewer gases are sometimes odorless and lethal). A cross connection is never going to cause a problem until one day it just does. Suddenly one day it can really, practically, seriously and lethally cause a "public health problem". Although the probability is low, who will guarantee you that No one will ever sue you and that you will never feel guilty about your plumbing? As you are persistent, perfectionist and persevering, you may appreciate my telling you what I think may help.

Conclusion: air gap is a good thing. With no garbage disposer, it is easy to hide, in the drain.

David