[mamelukesabre]

I doubt you understand the principle. Supply pipes are pressurized and full, as in no air space. Sewage pipes are what is referred to as open channel flow. THey can’t meter that very easily.

[RandallFlagg]

I work in a brewery. We have readers installed all over the place to tell flow and temps of all fluids going in and out of the plant. Pressurized, gravity fed, you name it, they read it.