Keeping some of your dish soap in a spare bottle pre-mixed with water, ready to apply to rags, paper towels or sponges, seems practical to quickly clean up small spills etc - the question is, is there a risk of making the soap itself "perishable" that way, possibly breeding germs that will be distributed by using it?

I am aware that the soap is not a food, however it is something commonly used near food and on food contacting surfaces.

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    My gut feel is that by the time you cut it enough with water to not kill bacteria it would be so diluted to have no cleaning power. – paparazzo May 1 '17 at 16:06
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    Some of the stuff on the market is labeled 'ultra', and supposedly you need less of it ... so I would assume at the very least you'd be able to dilute to 'normal' strength. But also consider that we water down soap when we wash our hands, and that still kills bacteria. – Joe May 1 '17 at 17:08
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    @dougal3.0.0 That is a different question than I am reading. OP please clarify. – paparazzo May 1 '17 at 17:35
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    @rackandboneman: ...what is it that diluting preservatives can lead to? – Lorel C. May 1 '17 at 20:12
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    Rendering them ineffective, microbes suddenly consider the preserved good nicely seasoned :) – rackandboneman May 1 '17 at 20:32

Molds can often live off even undiluted detergents.

I had discarded contaminated opened bottles more than once, one in recent weeks. There was growth near the nozzle and black streaks suspended in the liquid body. Given the viscosity of typical detergents, it is probable that droplets of contaminated water nurtured the growth and perhaps not the detergent itself. Either way, I would end up dispensing microbes, pathogens or not. Bigger concern is what can be lurking in other bottles without visible signs.

A quick search came up with this "Danger In The Soap Dispenser" article on albeit hand soaps rather than dishwashing soaps and bacteria rather than fungi which are sometimes more resilient.

  • Can you support this statement with any sources? – Catija May 2 '17 at 18:52
  • I have not looked, but I have recently discarded an opened bottled for that and it was not the first time. – user110084 May 2 '17 at 18:54
  • Was the entire bottle contaminated or only the surface? I don't really think that there's enough information here for this to be an answer. – Catija May 2 '17 at 18:56
  • I am happy to withdraw that. – user110084 May 2 '17 at 19:10
  • It was intended as a comment rather than an answer. A quick search came up with this: cmmonline.com/articles/231966-danger-in-the-soap-dispenser, about hand soap rather than dish detergent. What I had discarded has growth around the nozzle and also black streaks suspended in the body of the liquid. Given the viscosity, it is quite probable that contaminated water droplets were trapped inside the detergent body. In any event, the was growth inside (pathogens or not). – user110084 May 2 '17 at 19:20

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