My female friend went on holidays and i saw her treating an infection, she said she contacted it using the water system toilet, is it possible? was she lieing?

yes it is,
public toilets are very unhygienic

not public toilet. family toilet, and she happens to be the only one

family toilet can also be very unhygienic ,
and then u also have to consider that humans are not all equal. some of us are very sensitive and tend to pick up infections

but by the way: what is ur business with the lady's infection?? Are u her boyfriend or her doctor

Do you think people dont move about on NL? Arent you the virgin dude wanting to dump his girl because she is not a virgin?