If the sewer backs up and floods the basement, a check valve can be installed in the sanitary sewer discharge line. These valves are relatively expensive, but may be worth the cost if what you want is peace of mind. Drain sealing caps can also be obtained which fit in the top of the drain and tighten when screwed down. A rubber flange expands when the screw is tightened, securing the cap and preventing backflow. Most hardware stores carry these caps.

Septic backup is most common in older homes which do not have check valves, where the storm sewers and sanitary sewers and joined at some point and can be overwhelmed in heavy rains or floods. This is covered in Section T of The Home Waterproofers Manual – Home Waterproofing A to Z. Remember, in the waterproofing business it’s “buyer beware”. Most salesmen get a percentage of the sale and don’t consider it their job to save you money. They charge as much as they can. If they see a problem that can be fixed inexpensively, they won’t mention it, but will only talk about “preventing serious damage” and try to scare you into signing a big contract.

You can save thousands of dollars and many headaches by learning what is going on first. Often what looks like an expensive and serious problem may not be. Once the problem is explained, solving it is just common sense. I’ve used the knowledge I’ve put in The Home Waterproofers Manual – Home Waterproofing A to Z every day to fix water problems. It will work for you too.

But remember, when dealing with salesmen, in the waterproofing business it’s “buyer beware”. Most get a percentage of the sale and don’t consider it their job to save you money. They charge as much as they can. If they see a problem that can be fixed at low cost, or one that has a simple solution, they won’t mention it, but will only talk about “preventing serious damage” and try to scare you into signing a big contract.