Hopefully someone can give me some advice.......

I need to get a waste pipe past a dish washer. The only way I can get the
pipe past the washer and have the washer far enough back to sit flush with
the units is the chase the wall out and sink part of the pipe partly into
the wall.

The wall is constructed of grey bricks approx. 22x7 cm. (Don't know the
depth). Can anyway advice me if this is a bad idea and if not how deep I
should chase the wall out without *any* risk.

The washer has a recess at the bottom for running pipes but this is actually
10cm lower than the inlet into the main waster pipe in the flats!, so unless
anyone knows how to make water run upwards is chasing the wall out my only
option.

Thanks in advance.