I live in Brooklyn, NY. I own a 3 family building that was built in 2005. The basement floods only when there is extremely heavy rain. If I stop up the main sewer drain during the flooding - the water comes out of the toilet in the basement bathroom. We have one sump pump installed - but it doesn't really help when the rain is so heavy.

Our neighbor solved the problem by having a check valve installed and having a second more powerful sump pump installed - costing them $5,000.

Is there a less expensive way to solve this problem? Would the Flood Guard check valve work in this case? We need to prevent the water from coming up from the main sewer drain and from the toilet.

You may be suffering from sewer overload and you can all the city/county to inspect the drain WHILE it's happening. Then they can fix it at their end.

The flood guard check valve will work for the basement drain, but not the toilet.

A back low preventer installed in the main line is the only sure way to prevent it. A more powerful pump may not be necessary.

KISS pretty much covered it. Your sump pump has little or nothing to do with the problem. If it did the sumppump pit would be the point of flooding and not the toilet. Is you're the only building in the immediate area that has this issue? Like KISS said, this may be the city's problem and not yours.