illegal characters

Hello,
I am using postgresql to store data passed from a web page. A user may
enter whatever text she wants on that web page. Do I have to prepend all
the illegal characters in the text with backslashes before storing the
text in the database? Is there any way to make postgresql prepend these
illegal characters for me?
Example:
I have an entry 'foo/bar' in a database table (it was stored as
'foo/bar' NOT as 'foo\/bar', when I try to search for all rows that
contain entry 'foo/bar', I get no results.
Any help will be greatly appreciated.
Thanks