ELi5: Why can’t you boil a sponge to sanitize it?



Googling repeatedly tells you to just buy a new kitchen sponge, never boil them because it doesn’t work. But why wouldn’t it clean them?

In: Biology

It would clean it temporarily however you would weaken the structural integrity of the sponge by boiling it causing it to rapidly deteriorate.

[A study](https://www.nature.com/articles/s41598-017-06055-9#Sec2) found that it didn’t really help in the long term, even if it did have an immediate impact – and, in fact, it might make it *worse*.

> Sanitation by boiling or microwave treatment has been shown to significantly reduce the bacterial load of kitchen sponges and can therefore be regarded as a reasonable hygiene measure. However, our data showed that regularly sanitized sponges (as indicated by their users) did not contain less bacteria than uncleaned ones. Moreover, “special cleaning” even increased the relative abundance of both the *Moraxella–* and *Chryseobacterium–*affiliated OTUs. Presumably, resistant bacteria survive the sanitation process and rapidly re–colonize the released niches until reaching a similar abundance as before the treatment.

Tried boiling, microwaving, washing in dishwasher, washing in laundry, soaking in bleach. None work. The cleaned sponge seems “fresh” for a day maybe then stinks again.

Only solutions I’ve even found is to replace it

Wait- can’t we just have the sponge drink some bleach before we boil it?


Not sure if this is helpful, but I have found that the Dutch leave sponges on the windowsill for the sun to disinfect them.

For how long should we use a sponge? I’ve been using the same one for months.

The secret I’ve found to long lasting good smelling sponges is to always rinse them out after use, wring them out, and store them so they can completely dry out (I have a basket that suction cups to my sink). None of this boiling or dish washing needed.

I guess I take them for granted when I work for the US’s largest dish scrubber company. We hve bags of them that they give you to take home and pass out to family..

When I asked an engineer this they said:

Microwaving and boiling do sanitize better than no measures at all but you don’t kill everything in them and they repopulate quickly. Boiling and microwaving also don’t release the trapped food particles inside that lead to future infestations.

Boiling or microwaving will KILL the bacteria. What it won’t do is REMOVE the dead bacteria. That means there is dead biological material that’s just food for more bacteria. The more you sanitize the sponge, the faster more new bacteria will grow… ELI5-when you kill bacteria it becomes bacteria food.

Edit: Wow. So. Heat, UV, bleach & desiccation(alcohol/sanitizer) can all kill bacteria. But there is no practical way to clean the material out of the deep pores of a sponge without destroying it. Nothing is as good as a clean sponge.

A short video of a single celled organism dying that demonstrates this concept:

DISCLAIMER: I am by no means a subject matter expert nor do I represent big sponge corp.

LPT: Buy biodegradable sponges, and cut them in half. The smaller sponge is easier to handle and it makes the whole sponge last longer!

Does anyone have the specifics about our use and discarding of sponges? Somewhere I read we are creating significant environmental damage by throwing so many sponges away.