Kitchen Sink Drainage Confusion

[Twowaxhack]

Take a piece of hose and form an S trap.

make any shape you want.
Now pour water into the high end.

Does it drain out the low end ?

sure it will, no vent needed

 

[Twowaxhack]

What is going on in my opinion
the s trap is causing a back syphon
the no loop condition is causing a a back syphon in the opposite direction
these two are working against each other and causing an air look at the trap

Pick up the hose, tie it to the bottom of the counter
get rid of the strap and toss an a aav

For the dishwasher to be back siphoning the water would have to go somewhere, like filling up the dishwasher and then spilling out the front of the dishwasher.

Just like they do when there’s no check valve at the dishwasher pump, there’s no air gap, there’s no high loop and then the kitchen sink stops up.

I disagree with you but I do respect your theory.

 

[frodo]

yes i know i dont understand either...As i said i had zero problems until around 6 weeks ago, which is why the label thing doesnt make any difference.

the only thing the last plumber said was something about if the pipes had shifted that would cause feedback or something along those lines, whatever that means..

6 weeks ago is when your pipe became partially clogged

 

[Twowaxhack]

6 weeks ago is when your pipe became partially clogged

Bingo, that’s what I said.

 

[PeterW]

What is going on in my opinion
the s trap is causing a back syphon
the no loop condition is causing a a back syphon in the opposite direction
these two are working against each other and causing an air look at the trap

Pick up the hose, tie it to the bottom of the counter
get rid of the strap and toss an a aav


sinks will drain all day long with an s trap. they will stink but will drain


take a straw and put it in a glass of water. put your finger over the end of the straw and lift it out of the water
did it drain? nope. no vent
remove your finger, it drains it has a vent

Now that sounds like the best response ive heard so far, sounds credible to me. kind of feels air related to me. just a feeling.

could you link me UK versions of the parts you are talking about, if they screw on to existing pipework its a no brainer to replace. and i would like more space under the sink so maybe it can be arranged in such a way not to hang so far down.

 

[PeterW]

6 weeks ago is when your pipe became partially clogged

if its partially clogged then its partially clogged outside the property and outside my control. this sink is right against the external property wall, beyond what you see in the picture i have no control over, and im in a second floor flat. and as i said ive had two landlord appointed plumbes here who have used a hoover on the waste pipe and a wire snake, neither solved whatever the problem is.

I think its air related feedback as frodo said but im no expert.

 

[Jeff Handy]

I think the drain needs snaking by a plumber who knows what he or she is doing.
The clog is not outside the building, unless the apartment below you is also having problems.

 

[PeterW]

I think the drain needs snaking by a plumber who knows what he or she is doing.
The clog is not outside the building, unless the apartment below you is also having problems.

I dont think there is any clog due to all the previous posts and i have removed all the undersink myself up to the wall leaving the building and no clog but hey..

who knows. its a conundrum for sure...personally i think Frodo had the right idea about

For the dishwasher to be back siphoning the water would have to go somewhere, like filling up the dishwasher and then spilling out the front of the dishwasher.

Just like they do when there’s no check valve at the dishwasher pump, there’s no air gap, there’s no high loop and then the kitchen sink stops up.

I disagree with you but I do respect your theory.

yer dishwasher is working fine...its just filling the sink and the water sits there is all, dishwasher is not back siphoning for sure.

 

[PeterW]

So...

Normal use with dishwasher unattached sink drains fine at a normal speed without any problems whatsoever..

with Dishwasher attached whether its being used or im running a tap sink fills up and doesnt drain at all period, just sits there..

thats the fundamental problem which makes zero sense to me especially as everything worked ok for a year until 6 weeks ago..

and there are no blockages anywhere in the piping within this small area of the property.

 

[Riickk]

Sir...
If it worked correctly for a year (or was that 18 months?) and now it doesn't, doesn't that imply that something has changed?
You're insistent that the drain connections were done correctly.

What I think is the dishwasher's drain hose is coming up from the left into directly into the trap, and *below* the trap weir.
There is also, a corrugated drain hose (?) connected near the TOP of the drain line. Question: What does that hose connect to?

In the U.S. the drain hose from a built-in dishwasher would connect to the sink drain, close to the sink, and well above the weir in the trap.
That hose would have either (a) a loop of going up to the underside of the countertop -or- (b) be connected to an "air gap" on the countertop, which then goes back down to the drain. These connections are designed to keep water from backing up into the dishwasher.

I fail to see why fluid flow would be different in the UK.
You are certain that the dishwasher is correctly
connected per you local plumbing code.​

 

[Jeff Handy]

Just for grins, swap those two hoses, put the dishwasher hose on the top fitting.

And lift up the dishwasher hose as high in the cabinet as it will go, then secure it there with a clamp.

See what happens, it couldn’t hurt.

 

[Twowaxhack]

For kicks I dropped my dishwasher hose to the bottom of my cabinet and plugged my vent in the attic with a test ball.

My sink drains just fine.

 

[Twowaxhack]

This was even draining when I removed it .

only reason I was called is because the sink stunk like a dead body.

 

[tbdet]

I believe that your dishwasher drain hose probably was either higher in the cabinet and possibly got bumped or you may have had a backup that caused the dishwasher drain line to fill up with water and possibly drop down to its present location causing your current problem. If you just reach in and pick up the dishwasher drain hose it will be heavy as it is full of water since your drain will fill it up before the water goes completely through your trap. I believe that as you run water as soon as it covers the wye that attaches the dishwasher drain the volume of water in the dishwasher drain is much greater then the volume in the trap which causes the vacuum that is holding the water in the trap. If that is the case all you need to do is reach under the sink and raise the dishwasher drain line above the level of the trap. As you lift it water should run out into the trap and it will feel lighter. Holding it up (or tying it up as long as the bottom of it is above the top of the trap) try running water in the sink and if my theory is correct your problem will be solved. A few previous posts have suggested raising the line and that is the key but I'm sure that may not have made sense to you since you felt that it worked for at least a year but until that dishwasher drain hose was full of water and all of it below the trap it would not have caused your current problem.

 

[Hamberg]

Suggestion (from past experiences)...

You have $25US in plastic under your counter - replace everything, making sure you do the high-loop on the DW, it's above the trap and ELIMINATE that whole piece of the puzzle.

As has been noted by all of the regulars (who do this for a living), something changed 6-8 weeks ago; eliminate all of the obvious before searching for anomalies.

(point in case: I had a basement toilet that stopped draining after flushing (look back, think it was my original post). we tried sucking it out, snaking it out, removed the toilet and sucked it out and snaked it out, and got as far as (getting ready to) jackhammer the floor up to replace the trap and line. When... someone said toilets wear-out, replace the first piece of the equation and work forward. IT WAS THE TOILET!!!)

 

[havasu]

I have been administrating this forum for years (not paid, by the way, but volunteer like all of our helpers), and admit, this thread has me really stumped. I actually enjoy everyone's different thoughts and input in order to help this member. We appreciate you all!

 

[Twowaxhack]

It also stumped the two plumbers but they didn’t corrected the hose and S-trap so I’ve lost confidence in them.

So in my opinion it really hasn’t been looked at by a professional yet.

 

[tbdet]

Suggestion (from past experiences)...



As has been noted by all of the regulars (who do this for a living), something changed 6-8 weeks ago; eliminate all of the obvious before searching for anomalies.

i’m sorry if my first post offended anyone but I would think that correcting the gentleman’s problem would be the primary goal here no matter who posted it. I’m not guaranteeing it but since the entire dishwasher hose is below the trap it fills up when ANY water is run in the sink with the hose hooked up. After the dishwasher hose. Is filled the water rises in the drain until it’s above the trap where it would normally go through but with the DW hose full and below the trap the water in the trap has to PULL the weight of the water in the DW hose to overcome the vacuum created.
Raising the drain end of the DW hose even slightly above the trap would allow the source of the vacuum to be broken and allow the drain to work just as it does with the DW hose disconnected.

P.S. This may have been my first post but I am a licensed Journeyman Plumber!

 

[Twowaxhack]

i’m sorry if my first post offended anyone but I would think that correcting the gentleman’s problem would be the primary goal here no matter who posted it. I’m not guaranteeing it but since the entire dishwasher hose is below the trap it fills up when ANY water is run in the sink with the hose hooked up. After the dishwasher hose. Is filled the water rises in the drain until it’s above the trap where it would normally go through but with the DW hose full and below the trap the water in the trap has to PULL the weight of the water in the DW hose to overcome the vacuum created.
Raising the drain end of the DW hose even slightly above the trap would allow the source of the vacuum to be broken and allow the drain to work just as it does with the DW hose disconnected.

P.S. This may have been my first post but I am a licensed Journeyman Plumber!

Sorry but connecting a hose full of water to the the trap will not stop water from running through the trap from the sink located 12” above it.

Water runs down hill.

 

[frodo]

Hey PETER.
have you removed the tee that connects the dishwasher to the sink drain?

pull that sucker off and verify that it has or does not have a built in baffle

if it does that could be a problem

i still say. repipe the kitchen drain correctly
and run the hose to the drain as per the electra factory instructions
yes i looked them up