I am facing this same issue with a basement installation and plan to use a backwater swing check valve, available thru McMaster-Carr on the web.
The best way to prevent a sewage backup is to install a backflow valve. Once that is done, make sure to clean the valve regularly or it may not function properly.
Backup
There are many advantages of having backup and disaster recovery schemes in place. The most obvious is that even if the system crashes, the backup and disaster recovery schemes will prevent one from total loss.
A standby generator will provide backup power in the event of an electrical outage. You can get one that is fueled by diesel or kerosene and install it in your basement or backyard.
Have a plumber snake out the drain. You have some sort of blockage.
If you see a bear dont sream or make sudden movements!! Backup slowly!
So you can backup your data if data loss occurs.
No it is not ok as there are toxins in sewerage and some are quite harmful.=Why it happens is usually poor sewer /drainage piping is unmaintained properly=
A document cannot really be saved permanently. If someone decides to delete it, it can be deleted. To prevent this you should backup all your files, documents, photos, and music to an external source; preferably an online backup system.
A full backup
Go into a secure basement, tape your windows, stay on the first floor and have an evacuation plan and canned food and water and a portable raido with battery backup and flashlights down in the basement and a duffel bag of family medicines and bottled water too, try to work out an evacuation plan for when the tornado , passes, as well
If the existing sewer line is lower than basement grade (does it go into the basement floor and out of the house?) you can just connect in to the existing drain. By code, sewer lines must have a slope of 1/4 inch per running foot, meaning that raw sewage will run AWAY from the main plumbing stack of the house. If the sewer line is ABOVE the level of the basement plumbing fixtures, you will need to purchase and install a pump check-valve, and tank to install any plumbing below the house sewer line. If you have any questions, contact a licensed plumber to find out the needs of your home.