Dishwasher drain overflowing

[dvd7e]

Hi,

I have a rental property and ordered a dishwasher from Home Depot. I can do basic things but not much of a DIYer (unless I’m willing to sink a few hours into watching YouTube videos, but I don’t have much time these days) so I also got the full installation. But it is an older home (built in 1950s) and it’s a lower income property so there isn’t really much that is “standard” about the property, which is why the installers on delivery day said they wouldn’t do the installation, per Home Depot policy. Fortunately my Dad was visiting and in town and was able to take a stab at installation. Turned water on and no leaks, so went to test unit. First few minutes were ok as the dishwasher was filling with water, but as it went to drain into the S trap (see picture) it overflowed heavily out the top and I immediately shut unit off.

Tried adjusting drain hose to be closer to top of pipe to give it more clearance and that helped but same issue (I was ready this time with rags and bucket, etc).

Seems like trap might be clogged, will snake it out tomorrow. Any other ideas? Does this setup (drain hose to S trap) even make sense? Even if I get it unclogged am I running high risk of future clog and overflow with this setup?

FWIW….previous tenant said old dishwasher worked fine initially for about a year then leaked and she stopped using it for 8 years (this was all before I owned property). Now that she moved out I assumed it was an issue with dishwasher itself which is why I ordered new one, but she just clarified it was leaking in same manner (overflow out top of trap).

If snaking the trap doesn’t clear the overflow issue then I’m close to giving up and writing the dishwasher off as a $500 non-functional “fixture”. A dishwasher for this type of property would be an attractive feature but not a “must have”.

Please advise. Thanks in advance.

 

[MicEd69]

S-traps are not per code and could be your issue. After you are sure the line after the current S-trap is clear, you need to change the S-trap to a P-trap.

Replace the last 90 with a Sanitee, move the dishwasher standpipe 2"-3" to the left in your picture, install a vertical vent line from the Sanitee, and add an AAV at the top of the vent line above the dishwasher standpipe a minimum of like 2", more if you like. This should allow air into the drain line after the now P-trap which should allow the dishwasher standpipe to drain properly.

Sorry for the rough drawing.

 

[CT18]

Why are you connecting your dishwasher to a wash machine stand pipe. What about the drain under the sink

 

[dvd7e]

Why are you connecting your dishwasher to a wash machine stand pipe. What about the drain under the sink

Not for any reason other than there is no current hookup to sink and the stand pipe is there and that’s how it was hooked up before I owned the property. I’m having a plumber come on Monday to assess connecting to sink. Or converting to P trap per MicEd69

 

[Twowaxhack]

The drain is clogged. Try a pressure blow bag on it AKA drain bladder.

Google it and maybe watch a video.

The s trap is also improper. Should be a vented ptrap. First things first, get the drain flowing then address the improper trap.

 

[dvd7e]

The drain is clogged. Try a pressure blow bag on it AKA drain bladder.

Google it and maybe watch a video.

The s trap is also improper. Should be a vented ptrap. First things first, get the drain flowing then address the improper trap.

I snaked out the S trap with a snake auger, got it all the way thru the S portion and another 6-12” down. But that didn’t do anything, I didn’t feel any resistance, didn’t hear a clog removed followed by water flowing. But I retested the dishwasher and same result, still overflowing out the top. My best guess is that the double curve from S trap is just too much resistance and the water comes into the vertical pipe faster than it can flow thru the trap.

I’ll ask the plumber about either modifying/replacing S trap or feeding directly into sink drain

 

[Twowaxhack]

I snaked out the S trap with a snake auger, got it all the way thru the S portion and another 6-12” down. But that didn’t do anything, I didn’t feel any resistance, didn’t hear a clog removed followed by water flowing. But I retested the dishwasher and same result, still overflowing out the top. My best guess is that the double curve from S trap is just too much resistance and the water comes into the vertical pipe faster than it can flow thru the trap.

I’ll ask the plumber about either modifying/replacing S trap or feeding directly into sink drain

It’s a clog.

 

[dvd7e]

It’s a clog.

not agreeing or disagreeing, but is there a reason you say it’s a clog?

 

[MicEd69]

As I said in my initial response, I said, "After you are sure the line after the current S-trap is clear, you need to change the S-trap to a P-trap."

You need to snake from the current S-trap all the way to the branch that it connects to, or the main sewer line, not just 6" - 12" past the S-trap.

As Twowaxhack said, "Try a pressure blow bag on it AKA drain bladder." Until you know that line is clear, changing the drain to a proper P-trap is of no use except to bring things up to code.

 

[Twowaxhack]

not agreeing or disagreeing, but is there a reason you say it’s a clog?

Yes, water is backing up. That means a pipe is clogged.

 

[TomFOhio]

Water from a dishwasher doesn't drain that fast. Not like a washing machine.

 

[dvd7e]

Just following up….I had a plumber hook up drain hose directly to underneath sink, they charged $210

 

[Tim Whistler]

Just following up….I had a plumber hook up drain hose directly to underneath sink, they charged $210

Seems like a good way to go. Just make sure they capped that old drain so you don't get sewer gas when the trap dries out.