Plumbing in Moaning Myrtle's Bathroom

[dracojadon at yahoo.co.uk]

No: HPFGUIDX 150853

I had just typed out this post when I read the backlog of posts in my  
HPfGU folder, and found someone had just asked the first question,  
but I'm including it here for the sake of completeness, and because  
I'm not convinced there _wasn't_ a pre-Tom opening:

Who built in the sink at the entrance to the Chamber of Secrets? Tom  
had nothing to do with it - he said he _found_ the chamber. Did  
Salazar Slytherin have modern plumbers around? If not, who discovered  
the chamber before Tom did, ensured a disguised entrance was built  
over it, and what did they do there?

[The consensus seems to be that the castle magically shapes itself to  
include modern plumbing]

Point #2: Did they hatch the basilisk? Tom didn't (did he?), but how  
old is the basilisk? It's 20 feet long - that sounds small. The HP  
Lexicon says basilisks "grow up to 50 feet in length" and "can live  
for at least 900 years given an adequate food supply". (Is that from  
_Fantasic Beasts_? I don't have a copy here.) Is it really 1000 years  
old?
(Aside: did someone try to hatch a basilisk under Trevor at one  
point, or is that my imagination?)

The pipes in the bathroom sound semi-modern, too. Only the crumbling  
stone tunnel really sounds like it was built 1000 years ago. Building  
in the pipes sounds like major work, if they're younger than the  
chamber itself. Could it have been done in secret?

And who scratched the serpent onto the side of the tap "that's never  
worked" - that wasn't Tom. Myrtle knew that because she'd been using  
the bathroom before Tom found/used the chamber.

"dracojadon"