If you say that something is non-existent, you mean that it does not exist when you feel that it should. Hygiene was non-existent: no running water, no bathroom.

Is it non-existent or inexistent?

As adjectives the difference between inexistent and nonexistent. is that inexistent is nonexistent while nonexistent is not existent; not real.

What type of word is non-existent?

NON-EXISTENT (adjective) definition and synonyms | Macmillan Dictionary.