When you replace a toilet, install a low-consumption model or a water saver. Standard toilets use 5 to 7 gallons per flush; "water-savers" use 3 to 4 gallons per flush; and new low-consumption models use 1.6 gallons, or less per flush. Until you replace your toilet, put a plastic bottle filled with water in the tank to cut down on water needed for a flush.
Check Drain Plug: Install a floating floor drain plug at the current drain location. If the floor drain pipe backs up, the float will rise and plug the drain.
Install a Sewer Backflow Valve: If flood waters enter the sewer system, sewage can back up and enter your home. To prevent this, have a qualified, licensed plumber install an interior or exterior backflow valve. Check with your building department for permit requirements.
If you are retrofitting a backflow value, check with your building department for permit requirements. Be sure to talk to a professional home builder, architect, contractor or building supply retailer for other backflow mitigation tips.