Septic Line Question

[BillT]

I noticed a while back when I needed to find my septic line under ground that for a certain length, from the house to the tank, the plastic pipe reduces from 4 Inch to 3 Inch for what I believe is just a short distance. I was surprised to see this and it still puzzles me today to why someone would want to reduce it, but just wondering if there is possibly any kind of advantage to this?

Thanks

 

[Twowaxhack]

no advantage. If it’s working then it’s fine, not proper but fine.

 

[johnjh2o]

I noticed a while back when I needed to find my septic line under ground that for a certain length, from the house to the tank, the plastic pipe reduces from 4 Inch to 3 Inch for what I believe is just a short distance. I was surprised to see this and it still puzzles me today to why someone would want to reduce it, but just wondering if there is possibly any kind of advantage to this?

Thanks

Never reduce a line in the direction of flow unless it's a closet bend.