I am considering installing a backflow preventer to eliminate sewer water that backs up in the basement. Do you know if this device is installed inside the basement or outside the wall? Also do you have the name of a good company who could do the installation? I would greatly appreciate a response. Thank you.

It depends on how the sewer enters the house as to where a back flow preventer's locater. If you sewer is above grade in the basement then it goes inside. If the sewer enters on a slab or under the basement floor it's easier to dig down and install it on the sewer outside the house. Sorry! We don't recommend contractors. Get three estimates. Good luck, Tom

Speedball thank you for your quick response. You are very knowledgeable. You are a pro. Thank you.