I put 2 pans of water on to boil in one I use some of my clean dish water that has a bit of bleach and dish soap, ( About 2 capfuls of bleach to a whole sink or water) and one plain clean water. I take a small container , a small strainer and a spoon, Boil the water turn off and then clean cartos.
I put my cartos in the small container pour in some soapywater swirls with sppoon for a bit rinse in sieve repeat with clean boiling hot water, then soapy then clean till it is all gone then I run them under warm water of faucet for a few seconds each, strain, then take a bit of paper towel and twist it up and stick it in end after 5 mins they are all dry, clean and I have no previos flavor! Not sure if soapy/ bleach water is safe but it kills germs from letting people (borrow) and I dont have to worry about
vaping any residue as I rinse this all out well!