Santiago Jimenez:
Does it say on the texts how someone knows when all effluents have been released ? How does someone know they wont show up again ?
It just says "With release, there is the knowledge, 'Released.'".
Just as if there were a pool of water in a mountain glen — clear, limpid, and unsullied — where a man with good eyesight standing on the bank could see shells, gravel, and pebbles, and also shoals of fish swimming about and resting, and it would occur to him, 'This pool of water is clear, limpid, and unsullied. Here are these shells, gravel, and pebbles, and also these shoals of fish swimming about and resting.' In the same way — with his mind thus concentrated, purified, and bright, unblemished, free from defects, pliant, malleable, steady, and attained to imperturbability — the monk directs and inclines it to the knowledge of the ending of the mental fermentations. He discerns, as it has come to be, that 'This is stress... This is the origination of stress... This is the cessation of stress... This is the way leading to the cessation of stress... These are mental fermentations... This is the origination of fermentations... This is the cessation of fermentations... This is the way leading to the cessation of fermentations.' His heart, thus knowing, thus seeing, is released from the fermentation of sensuality, the fermentation of becoming, the fermentation of ignorance. With release, there is the knowledge, 'Released.' He discerns that 'Birth is ended, the holy life fulfilled, the task done. There's nothing further for this world.'
[
MN 039]
It's just from seeing so clearly that there is no longer any doubt.
Practically speaking, it's just a matter of practicing. Is there suffering in current experience? Then release has not happened yet. Is there apparently no suffering? Potentially, look harder. Ask around. See if there's anything you missed. But there will be no doubt when it happens as there will be no more ignorance (10th fetter).
Santiago Jimenez:
Edit: By the way, how in the hell do you guys make quotations? I bet it's obvious but can't figure it out, damn

You have a [ quote=name ] at the beginning, then the quote text, then a [ /quote ] at the end (without spaces between the square brackets). You are missing a [ /quote ] in your post (two [ quote=name ]s, only one [ /quote ]), so the formatting is all wrong.