This has been bugging me for WEEKS GUYS OMG

Okay, we know hogwarts was founded sometime in the tenth century. The Harry Potter wiki gives the date as 990. So logically Slytherin must have left the school by, oh, say 1070 at the latest. Slytherin made the chamber of secrets before leaving. Tom Riddle came along and opened it in the 1940s, and as far as we’re aware no one else knew how to open it or where the entrance was for that ~900 year gap. Said entrance being through a sink in a girls’ bathroom.

MY QUESTION IS: did Slytherin himself carve a snake into the water pipe in said bathroom? Does this imply that wizards had functional plumbing a good 700+ years before everyone else and didn’t share it with anyone? Selfish bastards.