Background explanation of plumbing layout: my bathroom is directly above
my kitchen, the soil stack for the bathroom runs through a boxed in
compartment in the kitchen, the bathroom sink and the bath drain into
the soil stack (I think). The bathroom is nicely tiled and I have no
access to the sink/bath wastes.
Problem:
From the kitchen when the toilet is flushed there is no excessive noise
from the soil stack or above the ceiling, however when you drain the
bathroom sink or run the sink taps it sounds like water is being poured
onto a flat surface or maybe like water falling into a shallow pool just
below where the sink is. Draining the bath makes no such noise.
Question:I *think* that the sink waste must have an odd elbow or
something on it which is causing the water to tumble down vertically
then hit the (near) horizontal run which is causing this splashing
noise. I am having the kitchen ceiling re-plastered soon so now is a
great time to open it up and have a look... the question is how should
the waste be arranged, a nice shallow angle all the way to the stack, as
few elbows as possible?

All advice appreciated!

GMC