Plumbing help!! PLEASE!!!

I have a very interesting situation with my kitchen sink. For about a week or so my kitchen sink has been backing up. It does it when we run the dishwasher and the faucet both. We snaked it about 40 ft and nothing. Used the baking soda/vinegar mixture and nothing. We then called a plumber and he snaked it 100ft and nothing. He was baffled as to what it could be. We checked the air vent for the sewer that is on the roof and it was clear. Then last night we found out that our next door neighbor is having the exact same problem with his kitchen sink. No other drains in both houses are having any problems with being slow or clogged-its just the kitchen sinks! We are so confused with this. I have called the water/sewer company and they are coming out today sometime but the man said he seriously doubts it is a problem on their end because other things would be backing up as well. Does anyone have any clues as to what this could be? I am so sick of not having use of my kitchen sink and dishwasher. Any insight would be so appreciated! THANKS!!!

I would see if someone could use a video scope , There could be a problem near the street pipe connection

Sorry i didn’t see no other drains are having any problems , First thing what size is the drain sink. And is it a new dishwasher. Still consider a video scope There may be something the snake is missing

Do you have a high loop on the diswasher drain hose? and where is the drain connected; before the trap, on a disposer, to the main drain line, ECT

Wayne is on to something here. I said I was going to stop giving advise but I may have to just taper off and wean myself gradually.

What it sounds like and I have experienced this myself and am lucky enough to have a master plumber for a next door neighbor. He makes a very good living doing nothing but clearing drains. This is fairly common in kitchen sinks.
Over time, there is a gradual build up of a waxy substance from the coagulated grease, oils, etc from dishes and dishwashers on the same drain. When you snake it the material is very soft and pliable in the center and the snake goes right through but does not remove the plug. It will often build up around wyes and joints where it can build much like a clogged artery. Both times it happened in my own home my neighbor removed it for me with a drain rotor. It is bladed tip on a very long auger cable the he ran down through the entire length of the drain line through two different clean outs. Near the septic tank I have an observation port (a hole cut into the top of the Main line with a cover plate) and you could see the slug of hardened grease go by when he cut it loose. Drain cleaners will not work on these.

The whole thing can be avoided by simply using regular household vinegar in the homes drains once a month (he told me this secret). Once you get it running clear again, keep a gallon of white cheap vinegar from the dollar store on hand and every month after you have run the dishwasher at night, just before you got to bed, pour the entire gallon down the kitchen drain and leave it. He said you should probably let the hot water run for a few minutes BEFORE you pour in the vinegar. Vinegar is a mild acid and will desolve and loosen the grease. He does this for all the local restaurants and he tells them to do this they either forget or figure it isn’t worth their time so he makes good money keeping their drains clear.

Doug never wean of the advice . It is priceless and the help and knowledge is great.
BTW i had the same problem I went out and bought a power auger went through no problem Proud as punch turn to the wife said there you go 10 minutes later I had a mop luckily in my hand not somewhere else .LOLOL. Line was about 1/2 full

Thanks. Yep, the grease tends to coagulate in the bottom of the pipe first which is of course where the water runs. Even though the water from the sink and dishwasher is usually hot, it cools very quickly once inside the pipes like in my home inside a cold concrete slab. The grease and oils cools and solidifies in the same spot over and over.

Now, if my wife and I could just be consistent in using the vinegar we could have avoided the second clean out. I have thought about buying one of the power augers myself. Harbor Freight has them on sell a couple of times a year for around $200+ and it costs about $85 per trip to the plumber. My neighbor did it for free the first time but I insisted on paying him the second time because we did not do what he had recommended.

I paid about 245.00 at lowes , i have used a fair bit but not on my stuff .

I have found that acid is not very effective on grease, but a harsh caustic works wonders. Instead of vinigar run baking soda, or caustic soda if you can get your hands on some, but be carefull it will burn your skin if you get it on you. This is what oven cleaner and engine cleaner is made of.