Ven. Hasapanna referred to this sutta in this Friday night talk at this point: YouTube
Having checked the Pāli, the sutta made more sense - kumbha = water-pots.
A full water-pot that is covered is most useful because the water is useful and there less opportunity for mosquitoes.
A pot (for cooking) didn’t make as much sense. 
Not sure if it is related but the Malay word: kumbahan has to do with sewage (root word is kumbah, dictionary says - washing).