In 1150 the You are not allowed to view links. Register or Login to view. had already installed a complete water pipe system ( this would still be the "WYSIWII" approach). I would rather assume that the pipes and basins in the VMS are predominantly allegorical representations. But this roof as a striking element could have been "borrowed". Think of the swallowtail merlons on You are not allowed to view links. Register or Login to view. ( and how the roof would look in You are not allowed to view links. Register or Login to view. 
).
The water pipe system: Cambridge, Trinity College MS R.17.1, You are not allowed to view links. Register or Login to view. - 285r
).The water pipe system: Cambridge, Trinity College MS R.17.1, You are not allowed to view links. Register or Login to view. - 285r