There are so many data storage options which are available to the modern consumer and business user. Long gone are the days when entire racks of punch cards or massive, expensive tape drives (which could hold a whopping five megabytes of data) were the only way you could ensure that what you wanted to be preserved actually would be preserved. Nowadays, you do not even need to keep your backed up data on-site. There are numerous different methods that you can use if you want to ensure that your data is backed up in such a way that even a natural catastrophe or terrible fire at your office (which you hope will never happen) could not stop your data from being usable and accessible to anyone who needs access to it.
If you like to keep things “close at hand,” you can always do the extremely low rent (but highly effective) method of purchasing a backup hard drive (such as the kind which comes in most types of laptops), a USB adaptor which allows that drive to hook up to a computer, and back up your files there. Once the files are safely into your inexpensive, portable data locker, locking it up in a traditional safe is a pretty secure way of knowing not only where your files are (as in, a place where even the best hacker will not get to them), but also that they will be safe if someone spills coffee all over your main computer and completely ruins it.
Of course, if you are more inclined to want to store your data somewhere that would be completely impervious to any kind of problems your office might encounter (such as a fire, an earthquake or a tornado), you have other options available to you. For instance, you could employ an off-site data center to manage your file backups. Or, to be cheaper than that, you could use Dropbox.