Never seen this before… waste pump mounted under kitchen sink. This is on the eleventh floor of an industrial loft conversion in downtown Chicago.
Why would they do this? Pump body has an air admittance valve… was it to save on running a vent to the roof? Unit was owned by a major commercial contractor (not present at inspection so I couldn’t ask). Aside from the “big boys with big toys” phenom, What reasons could there be for this?