Rails security: allowing slash as user input

I have a Rails 3.2.21 application. One of my users has an address with a slash in it (think Main Street 321 1/2). Currently, we filter out slashes, which makes this user's address invalid. How can I allow this address through without either disabling the validation for this particular address or allowing slashes globally (a huge security risk)? Is there a way I can encode the slash, put it into the database and encode it back to a slash upon retrieval?

Thank you!