This is our Mainline Backflow Valve in action keeping sewer water from coming back into our basement. We had 8" of snow melt the day before and then had 3-4" of rain that overwhelmed our city's sewer system (as usual). This valve worked as advertised and we are more than happy with it's performance during this backflow issue. Without this valve we'd have had at least 12" of sewage in our basement. Instead we only had a bit on the perimeter of the basement.
