I have a backwater valve installed in basement when home was constructed to meet code because mine it one of the lowest homes at the end of the street with a lift station. I have not had any problems with sewer back up but after 2 years without a problem now the waste from the basement bathroom is getting caught in the backwater valve and not flowing out to the sewer. Why is this and how can it be fixed?

I have a backwater valve installed in basement when home was constructed to meet code because mine it one of the lowest homes at the end of the street with a lift station. I have not had any problems with sewer back up but after 2 years without a problem now the waste from the basement bathroom is getting caught in the backwater valve and not flowing out to the sewer. Why is this and how can it be fixed?

Your backflow preventer/ sewer check valve,(see image) Has a flap that's hanging up solids and paper. The solution would be to open it up and either repair or replace it. Good luck, Tom