If your precious certificates and family research get water damaged through storm, flood or leakage, the State Library of Queensland has an excellent 3 page guide that you can download from here. It covers a variety of media, and gives safety suggestions for the cleanup, plus excellent advice as to how to best preserve your photos/videos/books/documents/etc. This comes from their Conservation Unit.
Click here to download it.
You also need to back up your data from the computer to an offsite place, and do it regularly. Suggestions are:
1. Buy a flashdrive and back up all of your genealogy (and email or whatever's important) to it. Store it in your garage (up high) in a plastic container so it's not affected by weather. If all your genes photos take up way too much room, buy a 1Tb drive, and store it similarly, but make sure it isn't going to get super hot or super cold in a garage. Perhaps reconsider where you put it, but do use a plastic container, and do make sure it's away from the house in case of fire or storm damage. Does a relative have a secure wine cellar you could leave it in? How about a bank vault? Consider just how valuable your family history and photos are to you.
2. Scan all of your certificates and email them to other family members, be they in the next street or across the world, requesting that they keep them, and also make a backup of their own genes data along with yours. That way, if you lose your computer AND your backup, someone else has got your certificates. They can cost hundreds of dollars to replace. Do the same with photos if you can.
3. Donate photocopies of certificates, photos and family trees to the big genealogy societies in your state or territory. They will put them in their collection. When you donate, ask for permission to access your file for copies if your originals are lost.
Remember, your work is only as good as your last backup. If that was 2 years ago, you could lose everything you've done in between.