These photos are of my sewage system and were taken at an inspection point right outside my house. I have had this issue for years and I don't know what the material is. I have tried changing dishwasher and washing machine products but it still appears, and there's quite a bit of it as you can see from the photo ... what you see would have appeared over the course of a few months probably. To describe the material it is like chalky but sticky and oily but still crumbly ... and its fairly white in colour the yellow is only on the outside really.

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2 Answers 2


This looks like the stuff I use to clean out of our grease trap: disposal garbage, dish soap and cooking grease. I think grease traps (residential) are a thing of the past but all this going into a septic system could definitely solidify.

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    It looks like natural grease to me, I worked in a hospital that had a large holding tank that was pumped to the treatment plant, it had similar grease buildup that we had to knock down with a steam hose every couple of months or the chunks ended up plugging the pumps. The kitchen had grease traps , I was glad I was only there to take air quality measurements while they blasted it down.+
    – Ed Beal
    Nov 6, 2019 at 19:06
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    Not one of my more pleasant memories..
    – JACK
    Nov 6, 2019 at 19:07
  • thanks ... when you say grease traps are a thing of the past I'm not exactly sure what you mean - do you mean they shouldn't be and that I should get one? Nov 11, 2019 at 14:53
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    @byronyasgur Our grease trap sprung a leak and when we went to the plumbing store they told us they weren't needed anymore and to just pipe it through. We checked a few more places with the same results. You might want to check local ordinances to get their take on it.
    – JACK
    Nov 11, 2019 at 15:46

Only a chemical analysis could tell you for certain. My best guess is that it is dishwasher soap and grease. I had similar substance in my washer/dishwasher field lines a few years back. My system is not connected to septic.

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