About once a year I have to snake my kitchen drain line using a motorized snake like the RotoRooter folks use. I finally bought a camera to inspect the drain and found this about 10-15' past the sink drain:

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This is a 1.5" PVC drain. It looks like something is peeling from the pipe wall. We're on a septic tank, so we're very careful about what goes down the drain - most organic matter goes into the compost bucket. In addition, we're vegetarians, so no animal fat is run down the drain. Nothing other than the kitchen sink feeds into this section of drain. About once a month we pour a couple of gallons of boiling water down the drain (in addition to boiling water drained from pasta and such). Over the years I've tried various chemical drain cleaners to no effect.

What might this be and more importantly, how do I clear it out?

  • Can be almost anything from a picture. Would try to get a sample to be sure/test. Off hand some kind mixture of mold/fungus/organic matter/vegetable fat. Water pipes will not look so good either if you take a look at them.
    – crip659
    Nov 20, 2022 at 0:20
  • @crip659 Every time I've snaked the line nothing comes back on the snake - the line just clears and the mystery remains.
    – Llaves
    Nov 20, 2022 at 4:28
  • Pipe is what? PVC? My gess from the pictures would be either fatberg, in which case lye (the wear gloves, wear goggles, not remotely safe drain cleaner that really works, if you are careful enough with it) should turn it to soap, or a huge excess of PVC cement inside the pipe, in which case cutting it out and replacing it is indeed your best bet.
    – Ecnerwal
    Nov 20, 2022 at 18:31

2 Answers 2


The only solution that I find to be somewhat logical is that there is no way I can tell what it might be.

However one thing is worthy of consideration.

If the pipe is not buried too deep, and the distance where it is buried is not a back breaking job. You can never go wrong no matter how you look at it to simply take out the pipe and install a new one.

And the next time you have to do this again... between you and me, it will be a very very long time.

That is the kind of solution that I will be immediately entertaining if I was in your position. But I realize I am not.

Take care my friend.

  • Unfortunately the pipe is beneath the concrete floor slab. Making matters even worse, the floors have radiant (hydronic) heating.
    – Llaves
    Nov 20, 2022 at 16:11

What happens to grease and oil when it cools down from liquid form ?.

It is resistant to all drain cleaners, they will not resolve it.

It does not decompose.

It has great adhesion properties.

Start by not pouring any fat (grease and oil) and be surprised.

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