But think about it: Why are they using boring ol' ordinary muggle plumbing?
This question came to mind during the second flick when the Basilisk was roaming the castle via the pipes.
Pipes!? Srsly? Is that the best the magical peeps could come up with?
As it happens, they didn't always use pipes.
In fact, there was a time when they didn't use anything at all for the bathroom.
The peeps at BuzzFeed found the answer in one of J.K. Rowling's Pottermore ebooks, Hogwarts: An Incomplete and Unreliable Guide which reveals a gross AF fact about the history of the wizarding world.
Brace yourselves for this...
EW EW EW EW EW!