After I get done washing the dishes there is often a decent collection of food scraps in the drain trap -- perhaps a few tablespoons worth. This is, of course, mixed in with some soap suds. If I put this into my compost, will it cause any problems?

Out of my 5 liter compost pail, there would be maybe 200 to 300 mL of this soapy food scrap mixture by the time it's full. The dish soap I use is advertised as natural and biodegradable, but the list of ingredients includes a few hard-to-pronounce chemicals and things described as preservatives.

1 Answer 1


The worse problem with dish soap water in composting medium is the salt which can prevent good composting and arm sensible vegetables once used. Maybe desalinate compost is possible?

If your product is said to be "biodegradable", this means its components will be decomposed in reduce time. However, there are various composting environment, I heard for industries in Europe there are (at least) 2 degrees of biodegradability, depending of the temperature reached inside the compost - the easiest being around 56°C - difficult to reach at home for a whole composting pile!

If you leave your compost 2-3 years in place before using it for your vegetables, I guess there will be few to no problem (compare this to what you'll get from vegetables you'll eat from conventional farming!)

  • How much salt would be an issue? In my case, I would guess each 5 L pail I dump in the compost would have 5-10 grams of salt.
    – LShaver
    Apr 28, 2017 at 16:48
  • It will depend on the concertation you 'll reach in the whole thing. If it's often washed out by rain or other green water, it should be ok. If it is the only water you add, I'd avoid it.
    – J. Chomel
    Apr 29, 2017 at 18:09

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