Installed on top of water system holding tanks. For the life of me, I cannot remember what they’re called and/or purpose is. Any help is always appreciated.
Air bleeder(float type)
You mean that thing with the hose that appears to make a cross connection directly into the sewer line?
I don’t think I’ve ever seen one of them, but it makes me nervous.
Actually it does look like an air valve, I’m just used to seeing them on the side of the pressure tank and not connected to the sewer
Backwash valve…
Was this a water treatment or storage tank?
Think you are seeing things, don’t believe it’s connected, but the photo sure makes it appear that way. 
I certainly hope so, but it sure looks like it’s tapped directly into the top of sewer lateral. I know that they tend to spit some water, which is why they have the hose connection. I just hope they didn’t terminate it as it appears in the pic.