Subject: Where do drains change there flowing direction?

Ok, drains in the northern and southern hemishperes flow in opposite 
directions.  Now the equator is the dividing line between the two 
hemispheres, so if the equator was running through the center of the 
room that you are sitting in now, and you had one toilet on the 
northern side and one on the southern side, would both of them flow in 
opposite directions?  Or is there some kind of a zone around the 
equator where they change?  And in that zone what do they do?  Do they 
change their flowing directions on a day-to-day basis, or do they just 
drain straight down, or something else?  I hope that you understand 
what I am trying to ask you, and any insight would be appreciated.  
Thanks

Re: Where do drains change there flowing direction?