How do I stop water backing up in my basement sewer?

Question: Water backs up in my sewer when it rains. How do I stop water backing up in my basement sewer?

Answer: To stop water from backing up in your basement sewer, install a backwater valve on the line inside the house or just outside of the house. A backwater valve has a flapper that allows the water to travel out of the house, but doesn't let water come into the basement.