An info bomb for your Thursday

I work with an engineer and our interactions go like this:

Hey, [engineer].
Blondie! What’s up, blondie?
So, I have a question for you.
Why aren’t you smiling, blondie? You never smile. What’s your problem, huh?
You know those water towers on top of buildings?
Yeah.
Are those actually used, still?
Yeah, they are. See, water pressure in the city naturally only goes up about five stories. So buildings that are higher than that, they’ll have a pump that pumps the water directly to the roof. That's their internal water supply.
So, the people in the building, all their water comes from the tank?
That's right. But lemme tell you something, that is why you never drink out of a water fountain in a building with a water tank.
Why?
Because, you ever looked in ona those things? You know how many dead pigeons there are floating around in there?
Right.