Smell from under sink / back of dishwasher

awec

Hi,

We have a pretty strong odor coming from under our kitchen sink, when we come down to the kitchen in the morning it immediately hits you. It's not a foul smell like sewage, more like dirty water.

I am pretty sure that the smell is related to the dishwasher (which is located right beside the sink), it seems to get worse after the dishwasher runs. It also explains why it's worse in the morning as we put the dishwasher on at night going to bed. The sink drains don't smell.

However the inside of the dishwasher smells fine, and the filters etc inside are all clean. I think the smell is coming from the back of it, I am suspicious that maybe it's not draining correctly?

I've attached a photo of the plumbing under our sink, and while I'm not a plumber I think it looks ok to me. The dark grey hose on the right hand side is the dishwasher dirty hose. The hose comes out the back of the dishwasher, runs horizontal for about half a metre and then loops up into this connection.

Everything else looks fine. Everything is dry. The waste pipes go into the big waste pipe in the ground and this has the usual rubber cap on it that looks fine, and fits snugly. No gaps that I can see.

A plumber looked at it about 8 months ago and the problem went away, but has returned again the past few months. Makes me think that he cleaned something out and it has built up again.

I've run dishwasher cleaner through it and when it's running the entire room smells like dishwasher cleaner. Not sure if it's normal that you'd smell it when the dishwasher is closed and running?

Haven't taken the dishwasher out to look at the back of it as I don't have the right sized spanner to get at it properly, but will do that next I guess.

Anyone any idea what could be going on here? Smell is starting to irritate me a lot, it can be quite strong making the whole downstairs smell!

Anyone have any insights or any idea what could be going on? Does everything look correct? Did a lot of googling and saw a load of results that the dishwasher waste hose needs to loop way up high before coming back down but all of these results were american and I am not sure if the same thing applies here!

Thanks!

awec

Under sink plumbing pic

awec

I am wondering if this big loop of horizontal waste hose could be the problem?

Washout

awec wrote: »

I am wondering if this big loop of horizontal waste hose could be the problem?

[img][/img]https://www.boards.ie/vbulletin/attachment.php?attachmentid=553968&d=1621870519

check the outside drain where kitchen pipes leads too..it gets clogged up with all sorts of things over time

Ive had a similar experience where I thought it was internal but It was the outside drain and when the wind was right it would blow smell into the house

meercat

Check that the blue blank is fitted tightly and all the nuts are twisted tight

Also put a jubilee clip on the waste hose instead of that tie wrap.

awec

meercat wrote: »

Check that the blue blank is fitted tightly and all the nuts are twisted tight

Also put a jubilee clip on the waste hose instead of that tie wrap.

All are tight.

greasepalm

Did you try running a dishwasher cleaner through it at highest temperature as any crap in the pipes will be cleaned out.
Did you pull dishwasher out and check for any dead bodies.

antodeco

awec wrote: »

Under sink plumbing pic

[IMG][/img]https://www.boards.ie/vbulletin/attachment.php?attachmentid=553967&d=1621870270

To the right of the water cut off, is that staining from a leak on the wall/plaster board?

MAJJ

awec wrote: »

Under sink plumbing pic

[img][/img]https://www.boards.ie/vbulletin/attachment.php?attachmentid=553967&d=1621870270

Have you checked all the u bends? Remove them clean them, clean pipes they are attached to. Have you unscrewed the circular inspection covers on those pipes?
I had same with washing machine and dish washer. After cleaning and running bleach and warm water the odours went away. But I did have residue built up and it was slowing/backing up and caused issues.

punisher5112

Have you checked the filter, any holes in the waste hose?

The smell could well be coming backup through the sink or just gunk sitting in bottom end of dishwasher, do you leave dishwasher door slightly open after use and oy close for the actual wash, this can prevent smells.

ClosedAccountFuzzy

Could be coming up from the overflows on the sink too. I'd suggest putting some bleach down the plug holes. Let it sit for a while and then flush it with tap hot water.

Wearb

Are the sinks draining quickly?
Check that P trap. If that gets restricted, sink water can flow back through that grey pipe.

ClosedAccountFuzzy

My only comment is you've a lot of unsupported pipework and a very heavy dishwasher aqua stop valve box hanging off it.

awec

greasepalm wrote: »

Did you try running a dishwasher cleaner through it at highest temperature as any crap in the pipes will be cleaned out.
Did you pull dishwasher out and check for any dead bodies.

I didn't get to pull the dishwasher out yet, will maybe do that tomorrow. Nothing dead there though, I can see behind it with my phone!

antodeco wrote: »

To the right of the water cut off, is that staining from a leak on the wall/plaster board?

No it's just a tear in the plasterboard paper.

MAJJ wrote: »

Have you checked all the u bends? Remove them clean them, clean pipes they are attached to. Have you unscrewed the circular inspection covers on those pipes?
I had same with washing machine and dish washer. After cleaning and running bleach and warm water the odours went away. But I did have residue built up and it was slowing/backing up and caused issues.

Will check the u-bend. What circular inspection covers do you mean?

punisher5112 wrote: »

Have you checked the filter, any holes in the waste hose?

The smell could well be coming backup through the sink or just gunk sitting in bottom end of dishwasher, do you leave dishwasher door slightly open after use and oy close for the actual wash, this can prevent smells.

I think it could be crap in the bottom of the dishwasher. The dishwasher filters are all clean though.

The dishwasher actually opens itself when it's finished running. The last hour of the drying cycle is done with the door open.

Wearb wrote: »

Are the sinks draining quickly?
Check that P trap. If that gets restricted, sink water can flow back through that grey pipe.

Sinks drain fine I think!

I'll check the trap anyway. Is it safe to just unscrew that? I assume once I'm not running the tap or the dishwasher it's grand. Bucket underneath to catch any crap.

Wearb

"I assume once I'm not running the tap or the dishwasher it's grand. Bucket underneath to catch any crap."

Yes.

awec

Wearb wrote: »

"I assume once I'm not running the tap or the dishwasher it's grand. Bucket underneath to catch any crap."

Yes.

Thanks I'll give that a look tomorrow.

Very frustrating problem as it's hard to find the source. Like if I found that dirty water was sitting in the dishwasher waste pipe or whatever, I still don't get how the smell would get out when the sink drains smell fine and internally the dishwasher smells grand!

I need to lower the dishwasher down to get it out and don't have a big enough spanner for the feet. Going to buy one tomorrow, pull it out and start sniffing round the back of it. I don't even know if there'd be anything back there except a solid metal back.

spuddy4711

Leave the sink stopper (or drain plug) in overnight. Half fill the sink with water. Block the overflow
inlet with tape. This will stop odour if it’s coming from sink.
Could it be coming from the dishwasher plug ? The rear of some dishwashers gets extremely hot. If the socket
is directly behind the machine, and the machine is pressed back, the plug top could overheat and create odour.

dathi

is there a trap directly underneath each of the sinks or is the trap at the bottom of the shared stack the only trap on the system

awec

dathi wrote: »

is there a trap directly underneath each of the sinks or is the trap at the bottom of the shared stack the only trap on the system

That trap at the bottom is the only one. Those 2 vertical pipes go directly into the 2 sinks.

punisher5112

That's where the smell is coming back up as I said, near 100% it's coming up from there, gunk, oils, fat etc build up, pipes then emit the smell when not in use.

awec

punisher5112 wrote: »

That's where the smell is coming back up as I said, near 100% it's coming up from there, gunk, oils, fat etc build up, pipes then emit the smell when not in use.

Would they not smell then if I stuck my nose in them? I'd expect the smell to be strong, but generally I can't smell anything bad when I put my nose in them.

The smell is way stronger under the sink than it is above the sink.

Gonna take out that trap and clean it anyway.

monseiur

Unscrew the very lowest fitting on the white ABS pipe in photo, then unscrew the fitting just above it to the right, remove U trap, give it a good wash out with detergent & small brush, then refit.
Beware this U trap will be full of gunk so place a bucket underneath.

awec

Just cleaned the trap. It was spotless clean. Don’t think that was the issue.

awec

So I took another look at the drain outside, right on the other side of the wall to the kitchen sink. Does this look right? There’s lots of sludgy crap.

MAJJ

awec wrote: »

So I took another look at the drain outside, right on the other side of the wall to the kitchen sink. Does this look right? There’s lots of sludgy crap.

[img][/img]https://www.boards.ie/vbulletin/attachment.php?attachmentid=554051&d=1621947051

[img][/img]https://www.boards.ie/vbulletin/attachment.php?attachmentid=554052&d=1621947051

Bingo and no to me that doesn't look right. I have a drain like that and every year I clean it as it has a number of flows coming from different directions. Normally water and jeyes fluid but it looks like you have grease so you may need warmer water/degreaser.

punisher5112

Fat and grease build up, the smell tends to come back up then nearly like a burp or better still fart.....

A good clear out is needed.

awec

So how do I clean that out? Can I do it myself or does it need some drain cleaning pros?

Is it normal to need to clean this often? We're only in this house 2 years, I don't think my folks have ever cleaned a drain in their house!

greasepalm

Have you not run the cleaner through through machine first as it cleans pipes also.
My pipe into drain think is 2 1/2" and got build up and had to run a long pipe cleaner through it.
Would ask if oil is poured down sink which is a big NO NO.

https://www.youtube.com/watch?v=kFlc_ha8lls

awec

greasepalm wrote: »

Have you not run the cleaner through through machine first as it cleans pipes also.
My pipe into drain think is 2 1/2" and got build up and had to run a long pipe cleaner through it.
Would ask if oil is poured down sink which is a big NO NO.

I ran the dishwasher with Finish dishwasher cleaner but that'd hardly clear that build up?

Creamy Goodness

awec wrote: »

So how do I clean that out? Can I do it myself or does it need some drain cleaning pros?

Is it normal to need to clean this often? We're only in this house 2 years, I don't think my folks have ever cleaned a drain in their house!

We've had this issue in a new build similar to yourself but smell came into hot press rather than kitchen. The cause - according to my neighbour (i.e. pinch of salt) - was a bad bend in one of the underground pipes (or joint, sorry my terminology is awful).

I ended up lifting the covers in the paths outside and running a hose through each pipe/bend in the pipe and ensure the water runs freely down all three. In my case I had three covers (one directly beside the sink, one in the corner of the house and one down the side alley of the house, ours was mainly loose waste (very little grease/fat) but still enough to cause a back up of smell.

awec

So if I picked up a bottle of something like this:

https://www.woodies.ie/jeyes-drain-unblocker-1-lt-326552

And put it down the manhole outside (or should it go down the sink), then left it for a few hours, then came and went at it with the hose, is that going to clear it you think? Should I be scooping some of that crap out first?

Creamy Goodness

awec wrote: »

So if I picked up a bottle of something like this:

https://www.woodies.ie/jeyes-drain-unblocker-1-lt-326552

And put it down the manhole outside (or should it go down the sink), then left it for a few hours, then came and went at it with the hose, is that going to clear it you think? Should I be scooping some of that crap out first?

Yeah I'd definitely go down that route of trying to soften it up and then blasting it with a hose. Scooping that **** up (no pun intended) is going to be super nasty.

From your previous troubleshooting it sounds like there's no issue with the internal pipes with regards to water flow (sink clearing fast etc.) and getting gunk to the outside it's just that it collects outside. I'd lash the jeyes down the drain

Must caveat, I'm be no means a plumber (bash keyboards all day) so if someone else comes along and tells me I'm a mad man please take their advice :pac:

greasepalm

My thoughts are from kitchen waste so in sink.

Under manhole before use try poking it to break it up and flush with hose and water.

How quick if running hot water is it gushing out into manhole.

So dishwasher is smelling nice now and might if needed jeyes .

you have stuck it the manhole i see poke to break it up and then flush with hot water from tap.

Having a few buckets of water to dump in gives more weight to shift it further along.


Having done that i might do a run through with dishwaher cleaner Finish also.

awec

greasepalm wrote: »

My thoughts are from kitchen waste so in sink.

Under manhole before use try poking it to break it up and flush with hose and water.

How quick if running hot water is it gushing out into manhole.

So dishwasher is smelling nice now and might if needed jeyes .

you have stuck it the manhole i see poke to break it up and then flush with hot water from tap.

Having a few buckets of water to dump in gives more weight to shift it further along.

Should I dump the buckets of water directly into the manhole? That won't cause any unintended backflow, right?

greasepalm

No as the hot water is running and is draining your just adding more volumn to push it out to clear as what i did a few years ago when i had a smell.
When cleans all points of flow show good flow from outside drains and sink.

Sorry yes buckets of water into manhole.

punisher5112

Lots and lots of hot water, break it up, if there is gunk you can remove by hand do so as it will only go further down and eventually build up and block, worst case.....

De greaser, fairy washing up liquid, Jeeves etc etc...

awec

The water flow seems to be in the opposite direction to what I thought, the yellow line is what I think the flow is.

Poking a bit cleared a lot!

The Mulk

awec wrote: »

The water flow seems to be in the opposite direction to what I thought, the yellow line is what I think the flow is.

Poking a bit cleared a lot!

[img][/img]https://www.boards.ie/vbulletin/attachment.php?attachmentid=554063&d=1621954428

Are you mid-terrace?
if so it could flow under your house out to the street.
I 've invested in drain rods and have used the pressure washer too. Have had no issued since, mine was a lot of sand from when i put down a patio and grease/food waste etc

awec

The Mulk wrote: »

Are you mid-terrace?
if so it could flow under your house out to the street.
I 've invested in drain rods and have used the pressure washer too. Have had no issued since, mine was a lot of sand from when i put down a patio and grease/food waste etc

End terrace.

The Mulk

awec wrote: »

End terrace.

There should be another AJ (manhole) that you can inspect, either at the side of the house or the front. See what they are like. There were two in my back garden. I cleaned mine from the one closest to the house until the next one. Once it was clean on my property i got on to Irish Water and told them the public drains needed to be jetted, they were out the next day

con747

I use one of these https://www.lenehans.ie/condor-flexible-wire-drain-cleaning-tool-5m.html to loosen any build up back into the house then fill all sinks with hot water and drain them at the same time so there's a good flow to shift anything in the pipes.

chooseusername

Lift the waste pipe off the floor and clip it to the underside of the worktop.

ClosedAccountFuzzy

The dishwasher pipe should definitely be looped up high and down. They’re really designed to be used to with a stand pipe as the default option.

Get wide pipe pipe support clip and lay the dishwasher drain tube so that it goes up to almost the top of the cabinet and then back down again into the drain connection. It should be nice and loose, just supporting the hose.


This should prevent any dirty water running back into the machine from the plumbing.

Bear in mind that most dishwasher don’t have a non return valve. The drain pipe is just connected straight to the drain pump. So it’s not gas tight. They rely on water in the sump / drain pipe itself to maintain a trap.

Your dishwasher might have come with a U shaped plastic device to make it hook into a standpipe. You can usually fit these further back along the pipe and often they’ll have a little hole for fixing them to a hook.

punisher5112

Oh I totally forgot the smell would be coming through the waste pipe where dishwasher waste goes in... If you could put some silicone around it just around the top, that might help.

awec

FuzzyThinking wrote: »

The dishwasher pipe should definitely be looped up high and down. They’re really designed to be used to with a stand pipe as the default option.

Get wide pipe pipe support clip and lay the dishwasher drain tube so that it goes up to almost the top of the cabinet and then back down again into the drain connection. It should be nice and loose, just supporting the hose.


This should prevent any dirty water running back into the machine from the plumbing.

Bear in mind that most dishwasher don’t have a non return valve. The drain pipe is just connected straight to the drain pump. So it’s not gas tight. They rely on water in the sump / drain pipe itself to maintain a trap.

I was thinking that. So the dishwasher waste pipe comes out the bottom of the dishwasher, it should go almost vertical up to the underside of the countertop, across and then down into the drain?

ClosedAccountFuzzy

awec wrote: »

I was thinking that. So the dishwasher waste pipe comes out the bottom of the dishwasher, it should go almost vertical up to the underside of the countertop, across and then down into the drain?

It should be going up, to almost the height of the dishwasher itself, at some point before it goes into the drain.

It doesn’t matter where it goes up, just as long as the pipe isn’t going horizontally into the drain.

Often they cut a hole high in the adjoining cabinet, and the hose runs up over that.

That will ensure that there’s volume of water in the dishwasher sump and also prevent any water from the sink trap back flowing into the machine.

They shouldn’t really run in at gradual slopes or horizontally.

Ideally, they’re connected to a standpipe and their own trap. The same is preferable for a washing machine. It just keeps things simple!

awec

FuzzyThinking wrote: »

It should be going up, to almost the height of the dishwasher itself, at some point before it goes into the drain.

It doesn’t matter where it goes up, just as long as the pipe isn’t going horizontally into the drain. That will ensure that there’s volume of water in the dishwasher sump and also prevent any water from the sink trap back flowing into the machine.

They shouldn’t really run in at gradual slopes or horizontally.

Would the dishwasher waste pump have enough welly to pump the water up at a steep angle?

I'd be surprised if water is flowing back from the sink given the way it's connected.

ClosedAccountFuzzy

Yeah it’s got plenty of power. You can hook a dishwasher or washing machine drain over the side of a sink without any issue. They usually have enough head to pump water out at a height maybe up to 30cm above the machine itself.

If you’ve any restrictions in flow of the trap and a large volume of water drains from the sink, you’d be surprised that can flow. It can also force gasses back into the dishwasher.

awec

FuzzyThinking wrote: »

Yeah it’s got plenty of power. You can hook a dishwasher or washing machine drain over the side of a sink without any issue. They usually have enough head to water out at a height maybe up to 30cm above the machine itself.

When I googled I saw this being suggested a lot but it was all on american sites and I wasn't sure if the same rules applied here.

Wearb

awec wrote: »

Just cleaned the trap. It was spotless clean. Don’t think that was the issue.

Was the trap half full of water. If working correctly, it should stop smells getting back into the house. Good idea to get a bit of height on that pipe from the dishwasher to prevent any sink waste getting into it.

ClosedAccountFuzzy

awec wrote: »

When I googled I saw this being suggested a lot but it was all on american sites and I wasn't sure if the same rules applied here.

Some machines (mostly the likes of Miele) have sophisticated non return valves. Miele literally has a large, metal ball valve, accessible in the sump, that prevents back flow into the pump and anti siphoning vents etc.

A lot of machines however, just rely on the loop of hose being at a sufficiently steep angle.

It’s generally advised to take a precautionary approach and just a avoid any backflow with an loop upwards.

Dishwashers usually provide a fairly decent length of drain hose too.