Double kitchen sink drainage problems

[Yamidb13]

Hi everyone,

I’m Tyler and I have plumbing problems lol

Our kitchen has a double sink and I just installed a new, first time garbage disposal beneath the right sink. Everything technically works and there are no leaks anywhere, however, the problems come in when filling both sinks (or just one for the matter) to test the drainage flow. It seems like there isn’t proper water and/or air flow so the water backs up into the other sink. There is lots of gurgling when the sink(s) finally do drain. I tried installing an aac vent and that doesn’t seem to have helped either. I’m posting pictures below in the hopes someone can tell me whether or not my install has obvious newbie mistakes or if the plumbing setup looks good and that maybe I have a different issue. Thanks so much I’m advance!

 

[voletl]

That trap is illegal and needs to be replaced with a properly vented p trap. Your vent is before the trap which makes it useless.

 

[voletl]

Red should be new drain orange should be new vent. Rip out what you have and start over.

 

[Yamidb13]

Red should be new drain orange should be new vent. Rip out what you have and start over. View attachment 18093

Thank you, voletl! I was wondering if that was the case based on some other similar posts I’ve seen, but wasn’t sure how exactly to put it together. I’ll put your setup together and check back in

 

[Yamidb13]

Red should be new drain orange should be new vent. Rip out what you have and start over. View attachment 18093

@voletl Hey, so I made the changes and it works much better. However, if I fill one sink up and pop the drain it backs up into the other sink. Is this possible to fix or is it just an unavoidable problem?

 

[nuecor]

View attachment 18094
@voletl Hey, so I made the changes and it works much better. However, if I fill one sink up and pop the drain it backs up into the other sink. Is this possible to fix or is it just an unavoidable problem?

You need to replace that fitting this fitting:

https://www.amazon.com/Danco-94010-...cphy=9051808&hvtargid=pla-307417755106&psc=1#

 

[nuecor]

https://www.amazon.com/Danco-94010-...cphy=9051808&hvtargid=pla-307417755106&psc=1#

 

[nuecor]

I'm sorry, I'm trying to paste the link but it isn't working ;-(

 

[RenewDave]

How old is the house? You probable should snake, or better yet jet that 1 1/2 drain line now that you will be putting disposal scrap in the line.

 

[Yamidb13]

How old is the house? You probable should snake, or better yet jet that 1 1/2 drain line now that you will be putting disposal scrap in the line.

The house was originally built in 1916, but I don’t know if or when the lines were replaced or snaked/jetted. I’m assuming you mean to snake or jet the main line by going down through the metal pipe coming up out of the floor? Is this just to ensure the lines are clear so that disposal waste doesn’t easily get caught on existing junk and clog the lines?

 

[Yamidb13]

You need to replace that fitting this fitting:

https://www.amazon.com/Danco-94010-...cphy=9051808&hvtargid=pla-307417755106&psc=1#View attachment 18096View attachment 18097

Hey @nuecor , thanks for the reply. Are you saying I need to replace my existing fitting with the fitting you suggest so that I’m up to code or so that when draining one side of my sink it will stop backing up into the other, or both?

 

[nuecor]

Hey @nuecor , thanks for the reply. Are you saying I need to replace my existing fitting with the fitting you suggest so that I’m up to code or so that when draining one side of my sink it will stop backing up into the other, or both?

Hi Yamidb13,

It's not for code it's because the fitting you've just used wasn't designed for that particular use, the one I've suggested has a baffle inside that diverts the water when released by dishwasher and water won't back up into sink.

 

[nuecor]

Sorry, I ment to say garbage disposal, not dishwasher ;-)

 

[Diehard]

Hey @nuecor , thanks for the reply. Are you saying I need to replace my existing fitting with the fitting you suggest so that I’m up to code or so that when draining one side of my sink it will stop backing up into the other, or both?

View attachment 18094
@voletl Hey, so I made the changes and it works much better. However, if I fill one sink up and pop the drain it backs up into the other sink. Is this possible to fix or is it just an unavoidable problem?

Chances are your drain lines are coated and causing it to run slow. Also, you should have used sanitary tees and not straight tees. That would have helped speed up the flow.

 

[Yamidb13]

Sorry, I ment to say garbage disposal, not dishwasher ;-)

@nuecor Ah, ok.

Chances are your drain lines are coated and causing it to run slow. Also, you should have used sanitary tees and not straight tees. That would have helped speed up the flow.

@Diehard Im thinking you’re right. Based on other terrible “jobs” the previous owner did himself, I’m sure these lines haven’t been properly cleared in a while. Nonetheless, I like knowing things are done well, so I’ll probably swap out both of my connections to sanitary tees. That being said, I don't actually see how the baffled end outlet T would stop water from backing up into the disposal sink on the right...All is seems to do is "guide" water by placing a baffle on the inside of the connection, which actually seems like it would just provide decreased flow and a place for disposal waste to be more likely to clog. Am I wrong on that?

In my simple mind, if I place sanitary tees where the horizontal line from the disposal meets the down tube for the left-side sink, and another where the horizontal line from the p-trap meets the vertical drain line and vent tube...then I will increase flow. Besides that, I think I'll likely have to get our lines professionally cleaned to ensure proper flow in the main lines, thus eliminating back flow.

Thoughts??

 

[Diehard]

@nuecor Ah, ok.


@Diehard Im thinking you’re right. Based on other terrible “jobs” the previous owner did himself, I’m sure these lines haven’t been properly cleared in a while. Nonetheless, I like knowing things are done well, so I’ll probably swap out both of my connections to sanitary tees. That being said, I don't actually see how the baffled end outlet T would stop water from backing up into the disposal sink on the right...All is seems to do is "guide" water by placing a baffle on the inside of the connection, which actually seems like it would just provide decreased flow and a place for disposal waste to be more likely to clog. Am I wrong on that?

In my simple mind, if I place sanitary tees where the horizontal line from the disposal meets the down tube for the left-side sink, and another where the horizontal line from the p-trap meets the vertical drain line and vent tube...then I will increase flow. Besides that, I think I'll likely have to get our lines professionally cleaned to ensure proper flow in the main lines, thus eliminating back flow.

Thoughts??

Yes, the idea is create a path of least resistance. Both when you change direction of the flow and insuring relative clear pipelines, all the way.

 

[frodo]

 

[Yamidb13]

View attachment 18101

@frodo Sorry, not 100% following your diagram. Are you saying to change the tee your circled to a glue type tee or the tee beneath your comment (above the main drain)? What’s the purpose or advantage of using a glue type tee? Also, which type of tee are you suggesting?

Secondly? When you say “clean out tee here,” do you mean to install a clean out tee or are you just saying that is where I should put the drain snake to clean out the pipes?

Thanks!

 

[frodo]

install, 2 -- 1 1/2'' pvc dwv sanitary tees and a 1 1/2'' fitting cleanout female adapter with plug
and use a proflex model # 3000-150 band to connect to the steel pipe

 

[Yamidb13]

install, 2 -- 1 1/2'' pvc dwv sanitary tees and a 1 1/2'' fitting cleanout female adapter with plug
and use a proflex model # 3000-150 band to connect to the steel pipe

Ok, gotcha. Do they have to be glue type connections for any particular reason? Also, what then would be the best way to route the dishwasher drainage that currently goes into the tailpiece that is connected to the metal drain pipe?

Thanks for your help!