I have configured my keyboard for French and US layouts. I cannot find a tilde anywhere on there.
Normally, the tilde (~) is on the upper case of the key to the left of the "1" character.
It is pretty essential if you use the terminal a lot, as it allows you to go to directly somebody else's home directory.
cd ~suzanne takes you to suzanne's home. Since, as a Linux user, I make a lot of use of the terminal, I really need the tilde.